Closes gh-15408

Closes gh-15409

Closes gh-15671

Closes gh-15669

Closes gh-15667

Closes gh-15668

Closes gh-15528

Closes gh-15529

This commit aligns the Spring WebFlux instrumentation on Spring MVC
since gh-12447.
From now on, if the best matching path pattern is not found,
the recorded uri tag will be "UNKNOWN".

Note that for WebFlux.fn, the pattern information is properly
recorded as of SPR-17395.

Closes gh-15609

This commit ensures that the compression options are also applied on the
`Http2Protocol` when http/2 is enabled with Tomcat.

Closes gh-15591

Closes gh-15639

Closes gh-15612

Closes gh-15611

Closes gh-15578

* pr/15583:
  Polish "Add unit test for cassandra health checker"
  Add unit test for cassandra health checker

Closes gh-15583

See gh-15583

* pr/15394:
  Polish "Avoid NPE when replacement property does not exist"
  Avoid NPE when replacement property does not exist

Closes gh-15394

See gh-15394

* pr/15536:
  Polish javadoc of ConfigurableUndertowWebServerFactory method

Closes gh-15536

* pr/15473:
  Optimize StringSequence

Closes gh-15473

Closes gh-15535

This reverts commit f9ce6c9d.

See gh-15505

See gh-15530

See gh-15529

See gh-15528

Closes gh-15239

Closes gh-15508

Closes gh-15507

Closes gh-15506

Closes gh-15505

Closes gh-15504