test: extend devctr sanity build to also run something inside docker

Have the sanity build also run a very small subset of our integration
tests inside the new docker container, to validate that the resulting
docker container at least roughly works.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

.buildkite/pipeline_pr.py

@@ -31,7 +31,7 @@
 if any(x.parent.name == "devctr" for x in changed_files):
     pipeline.build_group_per_arch(
         "🐋 Dev Container Sanity Build",
-        "./tools/devtool -y build_devctr",
+        "./tools/devtool -y build_devctr && DEVCTR_IMAGE_TAG=latest ./tools/devtool test -- integration_tests/functional/test_api.py",
     )
 
 if any(