Turn off uploading symbols for factory / firmware branches.
Turn off uploading symbols for factory / firmware branches.

There is no reason for factory / firmware branches to upload symbols.

BUG=none
TEST=unit tests.

Change-Id: I472a9880af4e09623da44ec616ac3a8202868595
Reviewed-on: https://gerrit.chromium.org/gerrit/46132
Reviewed-by: Peter Mayo <3d31fdaf44dc55bb1b4f50b19df9bc879177d37a@chromium.org>
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Commit-Queue: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Tested-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>

bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite,bpsinc-native/src_third_party_chromite,chadversary/chromiumos.chromite