We should prune when fetching remotes so that we don't attempt to sync deleted branches.
<rdar://problem/97036346>
Pull request: https://github.com/WebKit/WebKit/pull/2428
Committed 252512@main (78c97d5d2d89): <https://commits.webkit.org/252512@main> Reviewed commits have been landed. Closing PR #2428 and removing active labels.