Scale PS upload back to known committers

The current permissions allow anyone on the internet to driveby and
upload a PS.  Only active contributors to the project should be able
to do this sort of thing, so scale back access.

NB: Change owners can always upload new patchsets for their own CLs.

Bug: 507976856
Change-Id: I348f5e0614bfd03adf074ef7a9836244c4942242

groups

diff --git a/groups b/groups
index 10b10f1..9b2b28d 100644
--- a/groups
+++ b/groups
@@ -1,6 +1,7 @@
 # UUID                                                        	Group Name
 #
 25e1cfff90e3f648aa2acd2ee42818ea5b7177ce                      	gn-scoped
+2c3b20c962590555a3ccdc61545dbf84646b73c6                      	gn-committers
 403927c6ea7e2607dd8685c67463329745b869a1                      	autoupdate-service-accounts
 5c109e6b6e3bc0590371cb5ece58e716ada4b5da                      	SLSA Policy Verification Service Accounts
 ee87c80457698612d1b2a8cbc7d4ea4e8bb96f51                      	autoupdate-vigil-service-accounts

project.config

diff --git a/project.config b/project.config
index 63f8d38..4a0f3bf 100644
--- a/project.config
+++ b/project.config
@@ -12,7 +12,7 @@
 	read = group mdb/gn-gerrit-owners
 	revert = group Registered Users
 [access "refs/for/*"]
-	addPatchSet = group Registered Users
+	addPatchSet = group gn-committers
 [access "refs/for/refs/*"]
 	push = group Registered Users
 	pushMerge = group Registered Users