Only git operations should update the updated_unix column in repository table

[lunny]

Try to fix #32046

[silverwind]

I agree we should match Github behaviour and only update timestamp when git content changes. It's the most straightforward way to view this timestamp.

[silverwind]

Question is thought, shouldn't we make UpdateRepositoryCols default to not writing that timestamp and we could remove UpdateRepositoryColsNoAutoTime? If separate function is needed, I recommend naming it UpdateRepositoryColsWithAutoTime to indicate that auto-time behaviour is being opted in.

Also, as seen by the diff, there are a few places that don't use UpdateRepositoryCols, can we make them use it?