Bug 1653135: Sentry integration should handle incomplete settings r=firefox-build-system-reviewers,rstewart

In tests, the settings object doesn't have as many sections. When a section isn't
available, it raises an error.
The Sentry integration can interpret this error as telemetry being disabled.

Differential Revision: https://phabricator.services.mozilla.com/D83717

python/mozbuild/mozbuild/telemetry.py

@@ -347,4 +347,7 @@ def is_telemetry_enabled(settings):
     if os.environ.get('DISABLE_TELEMETRY') == '1':
         return False
 
-    return settings.build.telemetry
+    try:
+        return settings.build.telemetry
+    except (AttributeError, KeyError):
+        return False