Set manager as last ressort OWNERS

This limit how OWNERS appears on gerrit without limiting their
capability.
The main motivation for this change is to make sure the area owner are
the first default choice, without removing owner vote from bluetooth
project owners

Test: owner format check
Change-Id: I648ed8684453b4fb8c19ff5a04565817cafa8a82
Bug: 262605980

OWNERS

 # Project owners
-girardier@google.com
-muhammadfalam@google.com
-sattiraju@google.com
-siyuanh@google.com
-sungsoo@google.com
+girardier@google.com #{LAST_RESORT_SUGGESTION}
+muhammadfalam@google.com #{LAST_RESORT_SUGGESTION}
+sattiraju@google.com #{LAST_RESORT_SUGGESTION}
+siyuanh@google.com #{LAST_RESORT_SUGGESTION}
+sungsoo@google.com #{LAST_RESORT_SUGGESTION}
 
 # Per-file ownership
 

service/OWNERS

-# Reviewers for /service
-
-eruffieux@google.com
 mylesgw@google.com
-rahulsabnis@google.com
-sattiraju@google.com
-siyuanh@google.com
 wescande@google.com