[ci] get rid of ok-to-test label (#875)

Github requires approval for external users anyway:


https://docs.github.com/en/actions/managing-workflow-runs-and-deployments/managing-workflow-runs/approving-workflow-runs-from-public-forks

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Chores**
- Simplified conditions for running GitHub Actions workflows on pull
requests, removing dependencies on the "ok-to-test" label and repository
origin.
  - Updated comments to reflect the new workflow logic.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

.github/workflows/pull-requests-release.yaml

@@ -12,8 +12,8 @@ jobs:
       contents: read
       packages: write
 
+    # Run only when the PR carries the "release" label and not closed.
     if: |
-      contains(github.event.pull_request.labels.*.name, 'ok-to-test') &&
       contains(github.event.pull_request.labels.*.name, 'release') &&
       github.event.action != 'closed'
 

.github/workflows/pull-requests.yaml

@@ -12,20 +12,9 @@ jobs:
       contents: read
       packages: write
 
-    # ─────────────────────────────────────────────────────────────
-    # Run automatically for internal PRs (same repo).
-    # For external PRs (forks) require the "ok‑to‑test" label.
     # Never run when the PR carries the "release" label.
-    # ─────────────────────────────────────────────────────────────
     if: |
-      !contains(github.event.pull_request.labels.*.name, 'release') &&
-      (
-        github.event.pull_request.head.repo.full_name == github.repository ||
-        (
-          github.event.pull_request.head.repo.full_name != github.repository &&
-          contains(github.event.pull_request.labels.*.name, 'ok-to-test')
-        )
-      )
+      !contains(github.event.pull_request.labels.*.name, 'release')
 
     steps:
       - name: Checkout code