[CI] Only PR reviewers/committers can trigger CI on PR (#8124)

Signed-off-by: kevin <kevin@anyscale.com>

.github/workflows/add_label_ready_comment.yml

-name: Add Ready Label on Ready Comment
-
-on:
-  issue_comment:
-    types: [created]
-
-jobs:
-  add-ready-label:
-    runs-on: ubuntu-latest
-    if: github.event.issue.pull_request && contains(github.event.comment.body, '/ready')
-    steps:
-        -   name: Add label
-            uses: actions/github-script@v5
-            with:
-                script: |
-                    github.rest.issues.addLabels({
-                        owner: context.repo.owner,
-                        repo: context.repo.repo,
-                        issue_number: context.issue.number,
-                        labels: ['ready']
-                    })
-            env:
-                GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/reminder_comment.yml

@@ -15,7 +15,7 @@ jobs:
               owner: context.repo.owner,
               repo: context.repo.repo,
               issue_number: context.issue.number,
-              body: '👋 Hi! Thank you for contributing to the vLLM project.\n Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run `fastcheck` CI which consists a small and essential subset of CI tests to quickly catch errors. You can run other CI tests on top of default ones by unblocking the steps in your `fast-check` build on Buildkite UI. \n\nOnce the PR is approved and ready to go, please make sure to run full CI as it is required to merge (or just use auto-merge).\n\n To run full CI, you can do one of these:\n- Comment `/ready` on the PR\n- Add `ready` label to the PR\n- Enable auto-merge.\n\n🚀'
+              body: '👋 Hi! Thank you for contributing to the vLLM project.\n Just a reminder: PRs would not trigger full CI run by default. Instead, it would only run `fastcheck` CI which starts running only a small and essential subset of CI tests to quickly catch errors. You can run other CI tests on top of those by going to your `fastcheck` build on Buildkite UI (linked in the PR checks section) and unblock them. If you don't have permission to unblock, ping @simon-mo or @khluu to add you in our Buildkite org. \n\nOnce the PR is approved and ready to go, your PR reviewer(s) can run CI to test the changes comprehensively before merging.\n\n To run CI, PR reviewers can do one of these:\n- Add `ready` label to the PR\n- Enable auto-merge.\n\n🚀'
             })
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/remove_label_not_ready_comment.yml

-name: Remove ready Label on notready Comment
-
-on:
-  issue_comment:
-    types: [created]
-
-jobs:
-  add-ready-label:
-    runs-on: ubuntu-latest
-    if: github.event.issue.pull_request && contains(github.event.comment.body, '/notready')
-    steps:
-        -   name: Remove ready label
-            uses: actions/github-script@v5
-            with:
-                script: |
-                    github.rest.issues.removeLabel({
-                        owner: context.repo.owner,
-                        repo: context.repo.repo,
-                        issue_number: context.issue.number,
-                        name: 'ready'
-                    })
-            env:
-                GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}