Errors with DocumentTreeMacroIT with Mysql UTF-8

The problem is exposed through the integration tests of DocumentTreeMacroIT when using Mysql LTS UTF-8 with the following command:

xwiki-platform-index-test/xwiki-platform-index-test-docker$ mvn clean install -Dit.test=DocumentTreeMacroIT -Dxwiki.test.ui.database=mysql -Dxwiki.test.ui.databaseTag=lts -Dxwiki.test.ui.database.commands.character-set-server=utf8 -Dxwiki.test.ui.database.commands.collation-server=utf8_bin

It's probably a regression since 17.6.0: there's no failures when executing tests on 17.5.0.

The root cause is https://github.com/xwiki/xwiki-platform/commit/e657333c558e1beb6cfd82022d4a562bbb971023#diff-17bd9d91dce821d366ef166b8371dbadefaf1bf352ef1e5451ef85ca78616952R47 which sets the collation to utf8mb4_german2_ci instead of utf8mb3_german2_ci when the db collation is utf8mb3 (e.g., when running docker-al)