Bug 40795: Trim down tor-browser-build release prep issue templates

Merge Info

• Related Issues

  • #40795 (closed)

• Backport Timeline

  • Immediate - patchsets for critical bug fixes or other major blocker (e.g. fixes for a 0-day exploit) OR patchsets with trivial changes which do not need testing (e.g. fixes for typos or fixes easily verified in a local developer build)
  • Next Minor Stable Release - patchset that needs to be verified in nightly before backport
  • Eventually - patchset that needs to be verified in alpha before backport
  • No Backport - patchset for the next major stable

• Issue Tracking

  • Link resolved issues with appropriate Release Prep issue for changelog generation

Change Description

Trims down the release prep templates since with tor-browser#41649 (closed) the rebase and security backport tasks have their own issue templates

/cc @boklm @ma1 @dan @henry @pierov