[fenix] Rebuild toolchain if AndroidComponents.kt changes.

Initially we didn't want to do that since we do not need to cache dependencies from our own
maven repository. But Android Components can introduce other third-party transitive
dependencies from other repositories (like Android X) and those need to be cached.

taskcluster/ci/toolchain/android.yml

@@ -44,8 +44,7 @@ linux64-android-gradle-dependencies:
             - taskcluster/scripts/toolchain/android-gradle-dependencies.sh
             - taskcluster/scripts/toolchain/android-gradle-dependencies/**
             - buildSrc/src/main/java/Dependencies.kt
-            # We don't follow 'buildSrc/src/main/java/AndroidComponents.kt' because we only cache
-            # dependencies outside of the ones hosted on maven.mozilla.org.
+            - buildSrc/src/main/java/AndroidComponents.kt
         toolchain-artifact: public/build/android-gradle-dependencies.tar.xz
         toolchain-alias: android-gradle-dependencies
     treeherder: