Bug 1795042 - [ci] Migrate 'system-symbols' tasks from AWS -> GCP, r=MasterWayZ

Differential Revision: https://phabricator.services.mozilla.com/D159862

taskcluster/ci/system-symbols/kind.yml

@@ -24,7 +24,7 @@ job-defaults:
         platform: symbols/opt
         kind: other
         tier: 2
-    worker-type: b-linux
+    worker-type: b-linux-gcp
     worker:
         env:
             MACH_BUILD_PYTHON_NATIVE_PACKAGE_SOURCE: system