Fix #22672: Scroll parent of RepositoryCommitPage

Created by: pdubroy

Fix #21662 (closed): Make the diff view page scroll in the same way as the other repository subpages (e.g. Branches, Tags, etc.)

Old behavior:

https://user-images.githubusercontent.com/17293/124911312-e5772a00-dfec-11eb-9ec6-7375caa91523.mp4

New behavior:

https://user-images.githubusercontent.com/17293/124911174-bfea2080-dfec-11eb-829a-3ad6368dc5a3.mp4