fix(git): make the fetch revs use smaller revs to be less memory hungry, and less prone to fail

vcsserver/remote/git_remote.py

@@ -799,7 +799,7 b' class GitRemote(RemoteBase):'
         log.debug('Finished obtaining fetch refs, total: %s', len(fetch_refs))
 
         if fetch_refs:
-            for chunk in more_itertools.chunked(fetch_refs, 1024 * 4):
+            for chunk in more_itertools.chunked(fetch_refs, 128):
                 fetch_refs_chunks = list(chunk)
                 log.debug('Fetching %s refs from import url', len(fetch_refs_chunks))
                 self.run_git_command(