Fix clipping of authorization tables in experimental Manage Jenkins UI

[dhanush-raja-a]

Fixes #26171

Testing done

• Built Jenkins locally using mvn -Pquick-build clean install
• Started Jenkins with mvn -pl war jetty:run
• Enabled the experimental Manage Jenkins UI
• Navigated to Manage Jenkins → Security
• Tested Matrix-based and Project-based Matrix Authorization Strategy
• Verified wide authorization tables are no longer clipped
• Confirmed horizontal scrolling works and action buttons (Grant All / Remove All / Delete) remain accessible
• This is a CSS-only change; no backend logic was modified

Screenshots (UI changes only)

Before

After

Proposed changelog entries

• Fix clipping of authorization tables in the experimental Manage Jenkins UI

Proposed changelog category

/label bug, web-ui

Proposed upgrade guidelines

N/A

Submitter checklist

• The issue is well-described.
• The changelog entry is appropriate and in the imperative mood.
• There is an explanation as to why this change has no automated tests (CSS-only UI fix).
• No new public APIs or Java changes were introduced.
• UI changes do not introduce CSP regressions.
• No dependency updates are included.

Desired reviewers

@jenkinsci/core-pr-reviewers

[dhanush-raja-a]

My apologies for the multiple PRs and for posting in the wrong thread. I'm a first-time contributor and still learning the workflow. I've now addressed the linting errors in this PR