[release] Update Release Guide Instructions (#29919)

contributor-docs/release-guide.md

@@ -271,12 +271,6 @@ fixes. This is because bugs are always being introduced as part of normal
 development. We cut the branch to prevent new bugs being introduced and _then_
 we fix and cherrypick any truly release-blocking problems.
 
-In order to run this workflow, you will need to provide a Apache ID and Jenkins
-API token.  Your Jenkins API token can be generated by visiting
-https://ci-beam.apache.org, signing in with your Apache credentials, then going
-to `https://ci-beam.apache.org/user/<your username>/configure` and clicking
-`Add new token` in the API token section.
-
 - [ ] Run
   [cut_release_branch](https://github.com/apache/beam/actions/workflows/cut_release_branch.yml)
   (click `run workflow`)
@@ -353,13 +347,9 @@ issues that would block the creation of the release candidate.
        ```
        (cd release/src/main/scripts && ./verify_release_build.sh)
        ```
-    4. Trigger all Github Action and Jenkins PostCommit jobs from the PR created by the previous step.
+    4. Trigger all Github Action jobs from the PR created by the previous step.
        For GitHub Action jobs, they should be triggered by the pull_request_target event of a specific placeholder file
        added to the PR (`release/trigger_all_tests.json`), so no additional action should be needed.
-       You can run [mass_comment.py](https://github.com/apache/beam/blob/master/release/src/main/scripts/mass_comment.py) to do that.
-       Or manually add one trigger phrase per PR comment for Jenkins tests, or rerun the workflow for GitHub Action tests.
-       See [jenkins_jobs.txt](https://github.com/apache/beam/blob/master/release/src/main/scripts/jenkins_jobs.txt)
-       for a full list of phrases.
 
 - **Tasks included in the script**
    - Installs `hub` with your agreement and setup local git repo;