buildhistory: Drop git-gc call as obsolete

buildhistory used to result in many individual objects in the repo which
could affect performance. This gc call was added over a decade ago to avoid
those performance issues. Modern git calls git-gc when needed and this kind
of workaround should no longer be needed.

There is a small chance this is contributing to problems with the autobuilder
buildhistory repositories, so simplifying the code may help that too.

(From OE-Core rev: 0a88f9109f7670a6b188463a19392d445af6ff40)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/buildhistory.bbclass

@@ -877,7 +877,6 @@ END
 			# Porcelain output looks like "?? packages/foo/bar"
 			# Ensure we commit metadata-revs with the first commit
 			buildhistory_single_commit "$CMDLINE" "$HOSTNAME" dummy
-			git gc --auto --quiet
 		else
 			buildhistory_single_commit "$CMDLINE" "$HOSTNAME"
 		fi