NonceVerification: ignore unsetting of superglobal values

[jrfnl]

Bug Description

When all that's done with a superglobal value is to unset it, no nonceverification should be necessary.

Currently, the sniff will throw a warning for this:

 148 | WARNING | Processing form data without nonce verification.

Minimal Code Snippet

// OK.
unset( $_GET['meta-box-loader'] );

// Not okay.
do_something_with( $_GET['meta-box-loader'] );

For bugs with fixers: How was the code fixed? How did you expect the code to be fixed?

Error Code

WordPress.Security.NonceVerification.Recommended

Environment

Question	Answer
PHP version	any
PHP_CodeSniffer version	master
WPCS version	develop
WPCS install type	N/A
IDE (if relevant)	N/A

Additional Context (optional)

Might be a good idea to check in with the security team to confirm whether they agree with the above.

Tested Against develop branch?

• [x] I have verified the issue still exists in the develop branch of WPCS.

[jrfnl]

Loosely related to #1902 (and #187)

[dd32]

FWIW I fully agree with this - Unsetting is not processing, and warning for lack of nonces when it's not processing it is just extra noise.