Revert "Restrict access to release branch: release-R97 to LTS Refresher group."

This reverts commit 77a2b347d8c6b7356dbd78ab6da3a0dc3763d234.

Reason for revert: refresh done

Change-Id: I3d268b66fff89212181e9c5d3afbe27af35d39f0
Reviewed-on: https://cos-review.googlesource.com/c/All-Projects/+/59017
Tested-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Reviewed-by: Nandhini Rengaraj <nrengaraj@google.com>