Add Playground infra team to OWNERS on settings.gradle

This allows us to fix breakages on Github builds without waiting on
library owner.

Test: N/A
Change-Id: I870cc6568628baa888375d7607aa2a650f2d6f8f
diff --git a/appcompat/OWNERS b/appcompat/OWNERS
index d475b09..43a6878 100644
--- a/appcompat/OWNERS
+++ b/appcompat/OWNERS
@@ -4,3 +4,6 @@
 # For text related files
 [email protected]
 [email protected]
+
+# Per-file for Playground infra
+per-file settings.gradle = [email protected], [email protected]