SAT: assert `AIRBYTE_ENTRYPOINT` is set in a connector's Docker image

[sherifnada]

Tell us about the problem you're trying to solve

To support running connectors on Kubernetes, the connector needs to define the AIRBYTE_ENTRYPOINT env variable in its dockerfile like described in #3903.

Describe the solution you’d like

add a test to SAT which verifies that the connector's docker image defines this variable. This PR contains the java equivalent.