Reword mismatched-lifetime-syntaxes text based on feedback

Key changes include:

- Removal of the word "syntax" from the lint message. More accurately,
  it could have been something like "syntax group" or "syntax
  category", but avoiding it completely is easier.
- The primary lint message now reflects exactly which mismatch is
  occurring, instead of trying to be general. A new `help` line is
  general across the mismatch kinds.
- Suggestions have been reduced to be more minimal, no longer also
  changing non-idiomatic but unrelated aspects.
- Suggestion text no longer mentions changes when those changes don't
  occur in that specific suggestion.

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 419124d5144..f06757b3c23 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -55,7 +55,7 @@ mod invalid_from_utf8;
 mod late;
 mod let_underscore;
 mod levels;
-mod lifetime_syntax;
+pub mod lifetime_syntax;
 mod lints;
 mod macro_expr_fragment_specifier_2024_migration;
 mod map_unit_fn;