Coding standard issues.

Hi, I have fixed the possible coding standard issues.

There are few places where there are unused variables. The maintainer needs to verify that why they were used in the first place.

For example :

FILE: /Applications/MAMP/htdocs/drupal9.1.core.issues/modules/contrib/site_audit/src/Plugin/SiteAuditCheckBase.php
---------------------------------------------------------
FOUND 0 ERRORS AND 3 WARNINGS AFFECTING 3 LINES
---------------------------------------------------------
  87 | WARNING | Unused variable $static.
 277 | WARNING | Variable $opt_out is undefined.
 278 | WARNING | Variable $opt_out is undefined.
---------------------------------------------------------

<code>FILE: /Applications/MAMP/htdocs/drupal9.1.core.issues/modules/contrib/site_audit/src/Plugin/SiteAuditCheck/ContentVocabularies.php
---------------------------------------------------------
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
---------------------------------------------------------
 38 | WARNING | Unused variable $ret_val.
---------------------------------------------------------

Also for DI we have another issue, @see https://www.drupal.org/project/site_audit/issues/3163674,So DI fixes should be done in other issue and not the coding standard.

Please review.

I re-rolled the patch in #3 so it will apply now I will test

I have tested and the new patch works without causing any issues - committed