Change stumpy_moblab config to build only the base image
Change stumpy_moblab config to build only the base image

BUG=chromium:341558
TEST=compare the configs using `bin/cbuildbot_view_config`

Change-Id: Ia4ea7bd58b2b577fc4160a3229bafb69fe0aad8f
Reviewed-on: https://chromium-review.googlesource.com/185445
Reviewed-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Reviewed-by: Scott Zawalski <d0bc454f32175e2361d26fbdb5930ff6be11acc5@chromium.org>
Commit-Queue: Scott Zawalski <d0bc454f32175e2361d26fbdb5930ff6be11acc5@chromium.org>
Tested-by: Scott Zawalski <d0bc454f32175e2361d26fbdb5930ff6be11acc5@chromium.org>

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