review: fix TestSyncRebase test

Disable `advice.skippedCherryPicks` on the test client git repo to
suppress git's --reapply-cherry-picks hint when commits with same
content but different commit hashes are skipped on rebase.

Fixes golang/go#50453

Change-Id: I6d3a9cebf50f55c96d2ad096a58222c7988bcc61
Reviewed-on: https://go-review.googlesource.com/c/review/+/376039
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Trust: Heschi Kreinick <heschi@google.com>
Trust: Dmitri Shuralyov <dmitshur@golang.org>

git-codereview/sync_test.go

diff --git a/git-codereview/sync_test.go b/git-codereview/sync_test.go
index 6470c5e..31f4800 100644
--- a/git-codereview/sync_test.go
+++ b/git-codereview/sync_test.go
@@ -55,6 +55,9 @@
 	gt := newGitTest(t)
 	defer gt.done()
 
+	// Suppress --reapply-cherry-picks hint.
+	trun(t, gt.client, "git", "config", "advice.skippedCherryPicks", "false")
+
 	// client 3 ahead
 	gt.work(t)
 	gt.work(t)