Rollup merge of #102725 - nnethercote:rm-Z-time, r=davidtwco

Remove `-Ztime`

Because it has a lot of overlap with `-Ztime-passes` but is generally less useful. Plus some related cleanups.

Best reviewed one commit at a time.

r? `@davidtwco`

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -1637,7 +1637,7 @@ fn start_executing_work<B: ExtraBackendMethods>(
         llvm_start_time: &mut Option<VerboseTimingGuard<'a>>,
     ) {
         if config.time_module && llvm_start_time.is_none() {
-            *llvm_start_time = Some(prof.extra_verbose_generic_activity("LLVM_passes", "crate"));
+            *llvm_start_time = Some(prof.verbose_generic_activity("LLVM_passes"));
         }
     }
 }