Do not check coding standards in diff view

[str]

When comparing changes before commiting them, the PHPCS shows a lot of errors.

The errors on the "before" side, do not matter because you can't do anything for what was before. The errors on the "changes" side, do not matter neither because you are not editing the file, you are just comparing changes. If you want to see if your changes break any CS rule, go and edit it.

Also, the CS rules defined in the phpcs.xml are ignored in this view, so the broken rules shown in this view are wrong.