MINIFI-495 Provide an explicit dependency on minifi-assembly for the …

[apiri]

…minifi-docker project which makes use of the artifact in generating images.

Thank you for submitting a contribution to Apache NiFi - MiNiFi.

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For all changes:

• [ ] Is there a JIRA ticket associated with this PR? Is it referenced in the commit message?

• [ ] Does your PR title start with MINIFI-XXXX where XXXX is the JIRA number you are trying to resolve? Pay particular attention to the hyphen "-" character.

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