Conformance:use gateway api utility functions from v1.4.0 and minor fix typos.

[zetxqx]

What type of PR is this?

/area conformance-test
/kind cleanup

What this PR does / why we need it:

With the new gateway-api v1.4.0 released, some utility functions can be used to replace some duplication in the conformance tests. Key things leveraged:

1. now we can use utilities from gateway to send request with a body. using MakeRequestAndExpectEventuallyConsistentResponse
2. in expected response it can accept multiple status codes so we don't need the status wild card matching we have before.

Which issue(s) this PR fixes:

Fixes #1031

Tested against gkegateway:

--- PASS: TestConformance (680.70s)
    --- PASS: TestConformance/EppUnAvailableFailOpen (105.51s)
        --- PASS: TestConformance/EppUnAvailableFailOpen/Phase_1:_Verify_baseline_connectivity_with_EPP_available (81.26s)
        --- PASS: TestConformance/EppUnAvailableFailOpen/Phase_2:_Verify_fail-open_behavior_after_EPP_becomes_unavailable (0.65s)
    --- PASS: TestConformance/GatewayFollowingEPPRouting (116.99s)
        --- PASS: TestConformance/GatewayFollowingEPPRouting/should_route_traffic_to_a_single_designated_pod (0.81s)
        --- PASS: TestConformance/GatewayFollowingEPPRouting/should_route_traffic_to_two_designated_pods (0.80s)
        --- PASS: TestConformance/GatewayFollowingEPPRouting/should_route_traffic_to_all_available_pods (0.81s)
    --- PASS: TestConformance/HTTPRouteInvalidInferencePoolRef (34.43s)
        --- PASS: TestConformance/HTTPRouteInvalidInferencePoolRef/HTTPRoute_should_have_Accepted=True_and_ResolvedRefs=False_for_non-existent_InferencePool (34.10s)
    --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools (83.56s)
        --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools/Primary_HTTPRoute,_InferencePool,_and_Gateway_path:_verify_status_and_traffic (65.22s)
        --- PASS: TestConformance/HTTPRouteMultipleGatewaysDifferentPools/Secondary_HTTPRoute,_InferencePool,_and_Gateway_path:_verify_status_and_traffic (17.81s)
    --- PASS: TestConformance/InferencePoolAccepted (0.38s)
        --- PASS: TestConformance/InferencePoolAccepted/InferencePool_should_have_Accepted_condition_set_to_True (0.05s)
    --- PASS: TestConformance/InferencePoolHTTPRoutePortValidation (66.17s)
        --- PASS: TestConformance/InferencePoolHTTPRoutePortValidation/Scenario_1:_HTTPRoute_backendRef_to_InferencePool_with_Port_Unspecified (64.47s)
        --- PASS: TestConformance/InferencePoolHTTPRoutePortValidation/Scenario_2:_HTTPRoute_backendRef_to_InferencePool_with_Port_Specified_and_Matching (0.50s)
        --- PASS: TestConformance/InferencePoolHTTPRoutePortValidation/Scenario_3:_HTTPRoute_backendRef_to_InferencePool_with_Port_Specified_and_Non-Matching._Request_still_passing_because_HTTP_Port_is_ignored_when_inferencePool_is_backendRef (0.42s)
    --- PASS: TestConformance/InferencePoolInvalidEPPService (56.72s)
        --- PASS: TestConformance/InferencePoolInvalidEPPService/InferencePool_has_a_ResolvedRefs_Condition_with_status_False (0.05s)
        --- PASS: TestConformance/InferencePoolInvalidEPPService/Request_to_a_route_with_an_invalid_backend_reference_receives_a_500_response (23.95s)
    --- PASS: TestConformance/HTTPRouteMultipleRulesDifferentPools (66.76s)
        --- PASS: TestConformance/HTTPRouteMultipleRulesDifferentPools/Wait_for_resources_to_be_accepted (31.35s)
        --- PASS: TestConformance/HTTPRouteMultipleRulesDifferentPools/Traffic_should_be_routed_to_the_correct_pool_based_on_path (35.06s)
            --- PASS: TestConformance/HTTPRouteMultipleRulesDifferentPools/Traffic_should_be_routed_to_the_correct_pool_based_on_path/request_to_primary_pool (34.78s)
            --- PASS: TestConformance/HTTPRouteMultipleRulesDifferentPools/Traffic_should_be_routed_to_the_correct_pool_based_on_path/request_to_secondary_pool (0.23s)
    --- PASS: TestConformance/InferencePoolResolvedRefsCondition (144.97s)
        --- PASS: TestConformance/InferencePoolResolvedRefsCondition/InferencePool_should_show_Accepted:True_by_parents_and_be_routable_via_multiple_HTTPRoutes (26.42s)
        --- PASS: TestConformance/InferencePoolResolvedRefsCondition/Delete_httproute-for-primary-gw_and_verify_InferencePool_status_and_routing_via_secondary_gw (42.29s)
        --- PASS: TestConformance/InferencePoolResolvedRefsCondition/Delete_httproute-for-secondary-gw_and_verify_InferencePool_has_no_parent_statuses_and_is_not_routable (25.39s)

Does this PR introduce a user-facing change?:

NONE

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[zetxqx]

@robscott @danehans can you help take a look?

[nirrozenbaum]

This change lgtm.
leaving final stamp for our conformance masters 😃

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: nirrozenbaum, zetxqx

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• OWNERS [nirrozenbaum]

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[zetxqx]

/hold

This will need some rebase, waiting for other PRs to be merged.