Change testowners for deferred_components_test and android_views (#126872)

Changing to make @gmackall the owner of these tests. 

@reidbaker or @camsim99 let me know if either of you would prefer to take over, but I see both of you are already owners of some of these tests and I'm happy to take these ones on (I've already spent a little time looking into how they work for the ongoing debug signing key flake).
diff --git a/TESTOWNERS b/TESTOWNERS
index 2b85476..e58be66 100644
--- a/TESTOWNERS
+++ b/TESTOWNERS
@@ -282,9 +282,9 @@
 # Linux web_smoke_test
 /examples/hello_world/test_driver/smoke_web_engine.dart @yjbanov @flutter/web
 # Linux android views
-/dev/integration_tests/android_views @garyqian @flutter/android
+/dev/integration_tests/android_views @gmackall @flutter/android
 # Linux deferred components
-/dev/integration_tests/deferred_components_test @garyqian @flutter/android
+/dev/integration_tests/deferred_components_test @gmackall @flutter/android
 
 ## Firebase tests
 /dev/integration_tests/abstract_method_smoke_test @reidbaker @flutter/android