add gocritic/ruleguard checks back again, cleanup code. (#13665)

- remove some duplicated code
- reported a bug, separately fixed in #13664
- using strings.ReplaceAll() when needed
- using filepath.ToSlash() use when needed
- remove all non-Go style comments from the codebase

Co-authored-by: Aditya Manthramurthy <donatello@users.noreply.github.com>

cmd/admin-handlers-users.go

@@ -323,11 +323,12 @@ func (a adminAPIHandlers) SetGroupStatus(w http.ResponseWriter, r *http.Request)
 	status := vars["status"]
 
 	var err error
-	if status == statusEnabled {
+	switch status {
+	case statusEnabled:
 		err = globalIAMSys.SetGroupStatus(ctx, group, true)
-	} else if status == statusDisabled {
+	case statusDisabled:
 		err = globalIAMSys.SetGroupStatus(ctx, group, false)
-	} else {
+	default:
 		err = errInvalidArgument
 	}
 	if err != nil {