Keep unused annot on params

[som-snytt]

Fixes #23033

This commit just ensures unused annotation is retained for parameters. The previous tweak excluded constructor params (probably out of fear).

My limited understanding is that the meta annots decide what to do for fields: which elements receive the annotation.

For a class param, I assumed you don't know whether a param incurs a field until constructors. Does a using param always incur a field?

For the fix, follow the example of publicInBinary to retain the annotation.

A justification is that if I ask not to warn, I always mean don't warn about any of the things, so extra unused annotations is benign.

Should unused have the param meta annot? It is redundant because if there is a field, you will always use the param through a paramaccessor, which is either the field itself or the getter, and both will be annotated unused.

[som-snytt]

ok I'll run the whole test suite locally after switching to jdk 17 because it's impossible to tell from CI failures whether it is my fault.