quarkus.configuration.build-time-mismatch-at-runtime should be in the quarkus.config namespace

[gsmet]

We have several quarkus.config.* properties in the tree and we have quarkus.configuration.build-time-mismatch-at-runtime that is in a separate config root.

It should be moved to the quarkus.config root.
I'm not sure it's worth deprecating it properly as it seems very technical and probably not something people would widely use?

/cc @radcortez for advice.

[radcortez]

I agree. We can move it to quarkus.config.