Closes gh-9352

Closes gh-9347

Closes gh-9346

Closes gh-9229

Closes gh-9344

Closes gh-9298

Closes gh-9342

Closes gh-9335

Those properties are no longer honoured with Atomikos 3.8 and we're
using 3.9 by default.

Closes gh-9292

Closes gh-5591

* pr/9330:
  Polish

Closes gh-9330

See gh-9330

Closes gh-9252

Fixes gh-9253

Fixes gh-9295

Since SPR-15536, WebFlux.fn is now configured with `@EnableWebFlux`,
along the annotated controllers. Both `RouterFunction` and Controller
instances can now live within the same application and they share
the same web infrastructure.

This commit removes the custom auto-configuration for `RouterFunction`
and relies on `@EnableWebFlux` for that.

Closes gh-9165

Closes gh-9311

Closes gh-9310

Closes gh-9309

Closes gh-9308

Closes gh-9307

Closes gh-9306

Closes gh-9305

Closes gh-9304

Closes gh-9303

Closes gh-9302

* gh-9291:
  Polish "Adapt to relocated packages in Spring Data Cassandra"
  Adapt to relocated packages in Spring Data Cassandra