Auto merge of #114656 - bossmc:rework-no-coverage-attr, r=oli-obk

Rework `no_coverage` to `coverage(off)`

As discussed at the tail of rust-lang/rust#84605 this replaces the `no_coverage` attribute with a `coverage` attribute that takes sub-parameters (currently `off` and `on`) to control the coverage instrumentation.

Allows future-proofing for things like `coverage(off, reason="Tested live", issue="#12345")` or similar.

Author: bors