Suppress proguard warnings for mozilla.telemetry.glean.testing.**

The Glean SDK ships with classes used for tests as well. They are disabled
and not directly usable in production code: they throw if used there. They
can be used in tests just fine but, outside of tests, the test dependency
they use won't be there, hence the warning. It's safe to suppress these.

glean-core/android/proguard-rules-consumer.pro

@@ -8,3 +8,9 @@
 
 # Glean specific rules
 -keep class mozilla.telemetry.** { *; }
+
+# The Glean SDK ships with classes used for tests as well. They are disabled
+# and not directly usable in production code: they throw if used there. They
+# can be used in tests just fine but, outside of tests, the test dependency
+# they use won't be there, hence the warning. It's safe to suppress these.
+-dontwarn mozilla.telemetry.glean.testing.**