chore: use constant variable instead of hard code (#2560)

[ronething]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches
• Documentation
• Refactor
• Chore
• CI/CD or Tests

What this PR does / why we need it:

backport apache/apisix-ingress-controller#2560

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ ronething
❌ CiriAllen
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[github-actions]

conformance test report - apisix-standalone mode

apiVersion: gateway.networking.k8s.io/v1
date: "2025-09-23T08:54:34Z"
gatewayAPIChannel: experimental
gatewayAPIVersion: v1.3.0
implementation:
  contact: null
  organization: APISIX
  project: apisix-ingress-controller
  url: https://github.com/apache/apisix-ingress-controller.git
  version: v2.0.0
kind: ConformanceReport
mode: default
profiles:
- core:
    result: partial
    skippedTests:
    - HTTPRouteHTTPSListener
    statistics:
      Failed: 0
      Passed: 32
      Skipped: 1
  extended:
    result: partial
    skippedTests:
    - HTTPRouteRedirectPortAndScheme
    statistics:
      Failed: 0
      Passed: 7
      Skipped: 1
    supportedFeatures:
    - GatewayAddressEmpty
    - GatewayPort8080
    - HTTPRouteDestinationPortMatching
    - HTTPRouteMethodMatching
    - HTTPRoutePortRedirect
    - HTTPRouteRequestMirror
    - HTTPRouteResponseHeaderModification
    - HTTPRouteSchemeRedirect
    unsupportedFeatures:
    - GatewayHTTPListenerIsolation
    - GatewayInfrastructurePropagation
    - GatewayStaticAddresses
    - HTTPRouteBackendProtocolH2C
    - HTTPRouteBackendProtocolWebSocket
    - HTTPRouteBackendRequestHeaderModification
    - HTTPRouteBackendTimeout
    - HTTPRouteHostRewrite
    - HTTPRouteParentRefPort
    - HTTPRoutePathRedirect
    - HTTPRoutePathRewrite
    - HTTPRouteQueryParamMatching
    - HTTPRouteRequestMultipleMirrors
    - HTTPRouteRequestPercentageMirror
    - HTTPRouteRequestTimeout
  name: GATEWAY-HTTP
  summary: Core tests partially succeeded with 1 test skips. Extended tests partially
    succeeded with 1 test skips.

[github-actions]

conformance test report - apisix mode

apiVersion: gateway.networking.k8s.io/v1
date: "2025-09-23T08:55:14Z"
gatewayAPIChannel: experimental
gatewayAPIVersion: v1.3.0
implementation:
  contact: null
  organization: APISIX
  project: apisix-ingress-controller
  url: https://github.com/apache/apisix-ingress-controller.git
  version: v2.0.0
kind: ConformanceReport
mode: default
profiles:
- core:
    failedTests:
    - HTTPRouteInvalidBackendRefUnknownKind
    result: failure
    skippedTests:
    - HTTPRouteHTTPSListener
    statistics:
      Failed: 1
      Passed: 31
      Skipped: 1
  extended:
    result: partial
    skippedTests:
    - HTTPRouteRedirectPortAndScheme
    statistics:
      Failed: 0
      Passed: 7
      Skipped: 1
    supportedFeatures:
    - GatewayAddressEmpty
    - GatewayPort8080
    - HTTPRouteDestinationPortMatching
    - HTTPRouteMethodMatching
    - HTTPRoutePortRedirect
    - HTTPRouteRequestMirror
    - HTTPRouteResponseHeaderModification
    - HTTPRouteSchemeRedirect
    unsupportedFeatures:
    - GatewayHTTPListenerIsolation
    - GatewayInfrastructurePropagation
    - GatewayStaticAddresses
    - HTTPRouteBackendProtocolH2C
    - HTTPRouteBackendProtocolWebSocket
    - HTTPRouteBackendRequestHeaderModification
    - HTTPRouteBackendTimeout
    - HTTPRouteHostRewrite
    - HTTPRouteParentRefPort
    - HTTPRoutePathRedirect
    - HTTPRoutePathRewrite
    - HTTPRouteQueryParamMatching
    - HTTPRouteRequestMultipleMirrors
    - HTTPRouteRequestPercentageMirror
    - HTTPRouteRequestTimeout
  name: GATEWAY-HTTP
  summary: Core tests failed with 1 test failures. Extended tests partially succeeded
    with 1 test skips.

[github-actions]

conformance test report

apiVersion: gateway.networking.k8s.io/v1
date: "2025-09-23T08:58:07Z"
gatewayAPIChannel: experimental
gatewayAPIVersion: v1.3.0
implementation:
  contact: null
  organization: APISIX
  project: apisix-ingress-controller
  url: https://github.com/apache/apisix-ingress-controller.git
  version: v2.0.0
kind: ConformanceReport
mode: default
profiles:
- core:
    result: partial
    skippedTests:
    - HTTPRouteHTTPSListener
    statistics:
      Failed: 0
      Passed: 32
      Skipped: 1
  extended:
    result: partial
    skippedTests:
    - HTTPRouteRedirectPortAndScheme
    statistics:
      Failed: 0
      Passed: 7
      Skipped: 1
    supportedFeatures:
    - GatewayAddressEmpty
    - GatewayPort8080
    - HTTPRouteDestinationPortMatching
    - HTTPRouteMethodMatching
    - HTTPRoutePortRedirect
    - HTTPRouteRequestMirror
    - HTTPRouteResponseHeaderModification
    - HTTPRouteSchemeRedirect
    unsupportedFeatures:
    - GatewayHTTPListenerIsolation
    - GatewayInfrastructurePropagation
    - GatewayStaticAddresses
    - HTTPRouteBackendProtocolH2C
    - HTTPRouteBackendProtocolWebSocket
    - HTTPRouteBackendRequestHeaderModification
    - HTTPRouteBackendTimeout
    - HTTPRouteHostRewrite
    - HTTPRouteParentRefPort
    - HTTPRoutePathRedirect
    - HTTPRoutePathRewrite
    - HTTPRouteQueryParamMatching
    - HTTPRouteRequestMultipleMirrors
    - HTTPRouteRequestPercentageMirror
    - HTTPRouteRequestTimeout
  name: GATEWAY-HTTP
  summary: Core tests partially succeeded with 1 test skips. Extended tests partially
    succeeded with 1 test skips.