Delete our internal `OutputCaptureRule` since we not longer have any
tests using it.

* pr/17491:
  Delete ModifiedClassPathRunner
  Polish ModifiedClassPath support
  Migrate ModifiedClassPath tests to JUnit 5
  Add JUnit 5 ModifiedClassPathExtension
  Extract ModifiedClassPathClass logic
  Migrate to MockRestServiceServer
  Polish LoggingApplicationListenerTests
  Migrate to ApplicationContextRunner

Closes gh-17491

Delete `ModifiedClassPathRunner` since we no longer have any tests
that use it.

See gh-17491

See gh-17491

Migrate the remaining JUnit 4 tests to JUnit 5, making use of the
new `ModifiedClassPathExtension`.

See gh-17491

Add a JUnit 5 extension that allows tests to be run with a
modified classpath. Since JUnit 5 does not currently offer a way
to run tests with a different classpath, we instead fake the
original invocation and launch an entirely new run for each
method.

See gh-17491

Extract classes from `ModifiedClassPathRunner` so that they can
be reused.

See gh-17491

Migrate `RestClientTestWithoutJacksonIntegrationTests` to use
Spring's `MockRestServiceServer`.

See gh-17491

See gh-17491

Migrate a new tests to use the `ApplicationContextRunner`.

See gh-17491

Merge some string lines that were previously split because of the
90 chars wide formatting.

Update `OutputCaptureRule` so that it now implements
`CapturedOutput` and can be used directly with AssertJ.

Closes gh-17512

Closes gh-17506

* pr/17496:
  Test the Gradle Plugin against Gradle 5.5.1

Closes gh-17496

See gh-17496

* pr/17505:
  Polish

Closes gh-17505

See gh-17505

Align with the recent upstream Spring Framework changes triggered by
their issue #23170.

Closes gh-17492

Setting the log file name to a random value in smoke tests
doesn't work because the logger context has already been initialized.

Closes gh-17486

Using a random value for the logfile name caused
the logfile endpoint to return a 404 as the name
was resolved from the environment on every request.
This commit registers a bean for LogFile which is then
used by the logfile endpoint.

Fixes gh-17434

Closes gh-17025

Fixes gh-17484

* gh-17390:
  Allow build.time to be disabled so BuildInfoMojo's output is repeatable

Closes gh-17390

See gh-17390

Closes gh-17482

* gh-17480:
  Polish AbstractDependsOnBeanFactoryPostProcessor

Closes gh-17480

See gh-17480

Closes gh-17481

* gh-16627:
  Polish "Set up MongoClient beans' dependencies by type rather than name"
  Set up MongoClient beans' dependencies by type rather than name

Closes gh-16627

See gh-16627

See gh-16627

See gh-17128

Closes gh-17479