adds maven to image

[volatilemolotov]

• Adds maven to the image
• Sets MAVEN_HOME so there is no need to use -Pmaven_home gradle switch

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[volatilemolotov]

R: @damccorm

[github-actions]

Stopping reviewer notifications for this pull request: review requested by someone other than the bot, ceding control

[damccorm]

LGTM