bump maven to a version that's available on ibiblio

[pdurbin]

• Closes 404 for http://mirrors.ibiblio.org/apache/maven/maven-3/3.9.11/binaries/apache-maven-3.9.11-bin.tar.gz #414

Please note that I only bumped the version in the recent files. Maybe the others should be deleted some day? Here's a list:

% ack 'maven:' tests/group_vars -A1
tests/group_vars/vagrant.yml
349:maven:
350-  version: 3.9.12

tests/group_vars/jenkins.yml
341:maven:
342-  version: 3.9.12

tests/group_vars/java17.yml
307:maven:
308-  version: 3.8.8

tests/group_vars/postgres15.yml
306:maven:
307-  version: 3.8.8

tests/group_vars/payara_6.2025.10.yml
341:maven:
342-  version: 3.9.12

tests/group_vars/solr9_9260-vanilla-solr-src.yml
306:maven:
307-  version: 3.8.8

tests/group_vars/memorytests.yml
313:maven:
314-  version: 3.9.12

tests/group_vars/11639-db-opts-idempotency.yml
341:maven:
342-  version: 3.9.12

tests/group_vars/solr9.yml
308:maven:
309-  version: 3.8.8

tests/group_vars/solr_9.8.0.yml
339:maven:
340-  version: 3.9.5

tests/group_vars/payara_6.2025.2.yml
339:maven:
340-  version: 3.9.5

tests/group_vars/solr_9.8.1.yml
339:maven:
340-  version: 3.9.5