[fenix] No issue: perf code owner all /perf/ src dir.

Our previous strategy was to code owner all the specific files we should
own but that's fragile and unreasonable. This is simpler. We expect
there will still be edge cases that live outside these directories (e.g.
*Application*kt).

.github/CODEOWNERS

@@ -42,7 +42,12 @@
 # Therefore, we make the Perfomance team code owners of this file.
 /.github/CODEOWNERS @mozilla-mobile/Performance
 
-/app/src/*/java/org/mozilla/fenix/perf/** @mozilla-mobile/Performance
+# Own /perf/ src directories which typically includes perf code architecture
+# or code that monitors for perf regressions. This is our main way to own code
+# because it's simpler and less fragile than listing many specific files to own.
+/**/src/**/perf/** @mozilla-mobile/Performance
+
+# Possible regressions throughout the app
 *.pro @mozilla-mobile/Performance
 *proguard* @mozilla-mobile/Performance