Fix RestClientListener discovery for Reactive REST Client

[pravussum]

Fixes #23718

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[geoand]

Thanks for this!

Any chance we can get a test for this?

[pravussum]

I added a test & rebased on the current main.

[geoand]

Thanks!

[michalszynkiewicz]

@geoand I think you know Quarkus class loading better than me, if you say not passing the classloader to the service loader is better, let's merge it :)

[geoand]

Well, when we don't pass the ClassLoader, the JDK uses the TCCL, which is what we want :)