dev/ci: build images on any dockerfile change
Created by: bobheadxi
Expands on https://github.com/sourcegraph/sourcegraph/pull/36425 with the liberal building of all docker images if any Dockerfiles have changed, to catch issues like https://github.com/sourcegraph/sourcegraph/pull/37547 causing build failures in main
that should have been caught in PR.
Test plan
n/a