chore: fix some trivial problems and TODOs (#33473)

1. Fix incorrect `MentionCount` (actually it seems to be deadcode,
affects nothing)
2. Remove fallback sha1 support for time limit token
3. Use route middleware `reqRepoActionsWriter` for `ArtifactsDeleteView`
4. Use clearer message "Failed to authenticate user" instead of "Verify"
when auth fails
5. `tests/integration/benchmarks_test.go` is not quite right, actually
it is never used, so delete it.
6. Remove or update TODO comments

modules/web/middleware/binding.go

@@ -78,7 +78,7 @@ func GetInclude(field reflect.StructField) string {
 	return getRuleBody(field, "Include(")
 }
 
-// Validate validate TODO:
+// Validate validate
 func Validate(errs binding.Errors, data map[string]any, f Form, l translation.Locale) binding.Errors {
 	if errs.Len() == 0 {
 		return errs