Add playground owners to playground settings.gradle files

Test: N/A
Change-Id: Ic20251a7019dac91ed706e4884de3c684866e1e9
diff --git a/biometric/OWNERS b/biometric/OWNERS
index 471409f..11ca05f 100644
--- a/biometric/OWNERS
+++ b/biometric/OWNERS
@@ -1,2 +1,4 @@
 [email protected]
 [email protected]
+
+per-file settings.gradle = [email protected], [email protected]