[BUG] Gradle assemble task fails due to missing build.gradle files in docker subprojects

[evankielley]

Describe the bug
This is a follow-up to PR #4723 which removed build.gradle files from docker subprojects which, in turn, causes the gradle assemble task to fail.

To Reproduce
Steps to reproduce the behavior:

1. Ensure your local repo matches the remote -- ./gradlew clean
2. Run gradle assemble task -- ./gradlew assemble

Expected behavior
The gradle assemble task should succeed.

Plugins
None.

Screenshots

Host/Environment (please complete the following information):

• OS: Mac OS X
• Version 13.3.1 (aarch64)

Additional context
None.