Restrict access to release branch: release-R121 to LTS Refresher group.

BUG=b/475291916

Change-Id: Ib9de31ac6a15148a40f12e46b1171bc9745fd073
Reviewed-on: https://cos-review.googlesource.com/c/All-Projects/+/129701
Tested-by: Dom Huh <domhuh@google.com>
Reviewed-by: Kevin Liu <zhihuil@google.com>

groups

diff --git a/groups b/groups
index 421d09d..8e0412d 100644
--- a/groups
+++ b/groups
@@ -28,3 +28,4 @@
 mdb:kokoro-dedicated                                          	mdb/kokoro-dedicated
 mdb:kokoro-gob-readers                                        	mdb/kokoro-gob-readers
 fdcdd5531e58d7932f1f80c3913995e8daf7bc6b                      	LTS Refresher
+fdcdd5531e58d7932f1f80c3913995e8daf7bc6b                      	LTS Refresher

project.config

diff --git a/project.config b/project.config
index 0641560..b1c8ee3 100644
--- a/project.config
+++ b/project.config
@@ -180,3 +180,18 @@
 	pushMerge = block group Registered Users
 	submit = group LTS Refresher
 	submit = block group Registered Users
+[access "refs/heads/release-R121"]
+	create = group LTS Refresher
+	create = block group Registered Users
+	createSignedTag = group LTS Refresher
+	createSignedTag = block group Registered Users
+	createTag = group LTS Refresher
+	createTag = block group Registered Users
+	delete = group LTS Refresher
+	delete = block group Registered Users
+	push = group LTS Refresher
+	push = block group Registered Users
+	pushMerge = group LTS Refresher
+	pushMerge = block group Registered Users
+	submit = group LTS Refresher
+	submit = block group Registered Users