Rollup merge of #97166 - nnethercote:move-conditions-out, r=estebank

Rollup merge of #97166 - nnethercote:move-conditions-out, r=estebank

Move conditions out of recover/report functions.

`Parser` has six recover/report functions that are passed a boolean, and
nothing is done if the boolean has a particular value.

This PR moves the tests outside the functions. This has the following effects.
- The number of lines of code goes down.
- Some `use` items become shorter.
- Avoids the strangeness whereby 11 out of 12 calls to
  `maybe_recover_from_bad_qpath` pass `true` as the second argument.
- Makes it clear at the call site that only one of
  `maybe_recover_from_bad_type_plus` and `maybe_report_ambiguous_plus` will be
  run.

r? `@estebank`