This commit changes @SpringBootTest(randomPort = true) to
generate a random port for the actuator endpoints if the
management server runs on a different port from the main
server.

Closes gh-4424

Fixes gh-14463

See gh-14453

Reinstate `web` logging when devtools is in use, making use of the new
logging groups support. Devtools now also logs an `INFO` message
informing that properties defaults are offers an easy way to disable
them.

Closes gh-14450

Defer logging from devtools classes until the context is prepared.

Closes gh-14453

Add additional `switchTo` methods to allow a `DeferredLogger` to behave
like a regular logger once it has been replayed.

This commit also improves thread thread safety within the implementation.

Closes gh-14452

Provide a way for users to quickly group related loggers together for
easier configuration. The `loggers.group` property can be used to define
a group that can then be configured in the usual `loggers.level.<group>`
way.

Additionally, provide pre-defined groups for `web` and `sql.

Closes gh-14421

Closes gh-14445

Closes gh-14429

Closes gh-14418

Closes gh-14417

Closes gh-14158

Closes gh-14440

Closes gh-14424

Closes gh-14426

Closes gh-14442

Closes gh-14427

Closes gh-14430

Closes gh-14431

Closes gh-14432

Closes gh-14433

Closes gh-14434

Closes gh-14435

Closes gh-14436

Closes gh-14437

Closes gh-14439

Closes gh-14441

Add log4j to `spring-boot-actuator-autoconfigure` test scope so that
we get valid log output.

See gh-14148

Replace Aether dependencies with Maven Resolver following the Eclipse
EOL announcement for Aether.

Closes gh-7627