Closes gh-21889

Closes gh-21487

Closes gh-21784

Closes gh-21783

Closes gh-21776

Closes gh-21779

Closes gh-21782

Closes gh-21888

Closes gh-21781

Closes gh-21887

Closes gh-21886

Closes gh-21780

See gh-21885

Closes gh-21880

This commit aligns log4j2's behavior with logback such that loggers
with a null configuredLevel are also returned by the actuator endpoint.

Fixes gh-20037

Fixes gh-21293

See gh-21716

See gh-21716

Update the pipeline YAML to use ((milestone)) rather than ((branch))
when tagging docker images.

See gh-21716

Closes gh-21877

Closes gh-21876

Use YAML anchors and aliases to reduce the amount of repetition
in our CI pipeline YAML.

Closes gh-21716

Fixes gh-21036 in 2.3.1