chore: migrate to grpc-gateway/v2 and eliminate gogo/protobuf

[mmorel-35]

Description

Migrate to grpc-gateway/v2 and eliminate gogo/protobuf

k8s.io/code-generator v0.35.1 provides two critical flags:

• --drop-gogo-go: Generates protobuf methods using google.golang.org/protobuf instead of gogo (for .pb.go files)
• --keep-gogoproto=false: Removes gogo imports and annotations from proto files (for .proto files)

This allows manually-defined CRD types to coexist with protobuf serialization without duplicate type declarations.

Changes

Dependencies:

• k8s.io/code-generator v0.34.0 → v0.35.1
• All k8s.io/* packages updated to v0.35.1 (30+ packages with consistent replace directives)
• Added k8s.io/kubernetes v1.35.1 for compatibility
• grpc-gateway v1.16.0 → indirect dependency only (from argoproj/pkg)

Proto Generation:

• v1alpha1: go-to-protobuf --drop-gogo-go --keep-gogoproto=false
• Server protos: protoc-gen-go + protoc-gen-go-grpc (v2 tooling)
• All 103 .pb.go files regenerated without gogo imports
• Local plugin installation (dist/) eliminates network dependency

Code:

• github.com/grpc-ecosystem/grpc-gateway → github.com/grpc-ecosystem/grpc-gateway/v2/runtime (server.go, forwarder_overwrite.go, json.go)
• Removed gogoproto imports/options from server/settings/settings.proto
• Added jq filter to strip Kubernetes markers (+optional, +genclient, etc.) from swagger.json descriptions

Checklist:

• Either (a) I've created an enhancement proposal and discussed it with the community, (b) this is a bug fix, or (c) this does not need to be in the release notes.
• The title of the PR states what changed and the related issues number (used for the release note).
• The title of the PR conforms to the Title of the PR
• I've included "Closes [ISSUE #]" or "Fixes [ISSUE #]" in the description to automatically close the associated issue.
• I've updated both the CLI and UI to expose my feature, or I plan to submit a second PR with them.
• Does this PR require documentation updates?
• I've updated documentation as required by this PR.
• I have signed off all my commits as required by DCO
• I have written unit and/or e2e tests for my change. PRs without these are unlikely to be merged.
• My build is green (troubleshooting builds).
• My new feature complies with the feature status guidelines.
• I have added a brief description of why this PR is necessary and/or what this PR solves.
• Optional. My organization is added to USERS.md.
• Optional. For bug fixes, I've indicated what older releases this fix should be cherry-picked into (this may or may not happen depending on risk/complexity).

[bunnyshell]

❗ Preview Environment deployment failed on Bunnyshell

See: Environment Details | Pipeline Logs

Available commands (reply to this comment):

• 🚀 /bns:deploy to redeploy the environment
• ❌ /bns:delete to remove the environment

[reggie-k]

Thanks for the PR!
There is ongoing work on K8s client upgrade here:
#25767
If @chansuke is unable to work on #25768 , it is a good idea to address only the grpc-gateway/v2 in this PR.