Prevent saving unnecessary Jetpack post_by_email_address* DB options

[itsTallulah]

Description

This addresses the main symptom (autoloaded post_by_email_address* options being created per-user) of JP issue Automattic/jetpack#35636

Changelog Description

cleaner_jp_pbe_options uses pre_update_option_post_by_email_address* (where * is the current user ID) to prevent creation of unused NULL post_by_email_address* options (by returning the old_value in place of NULL, which in this case is no option at all).

Pre-review checklist

Please make sure the items below have been covered before requesting a review:

• [ 👍 ] This change works and has been tested locally (or has an appropriate fallback).
• [ 👍 ] This change works and has been tested on a Go sandbox
• [ 👍 ] Also tested live in a VIP test env (with this function in a standalone mu-plugin)
• [ n/a ] This change has relevant unit tests (if applicable).
• [ n/a ] This change uses a rollout method to ease with deployment (if applicable - especially for large scale actions that require writes).
• [ n/a ] This change has relevant documentation additions / updates (if applicable).
• [ 👍 ] I've created a changelog description that aligns with the provided examples.

Pre-deploy checklist

• [ n/a ] VIP staff: Ensure any alerts added/updated conform to internal standards (see internal documentation).

Steps to Test

1. Check out PR.
2. Login and visit the JP setting page in wp-admin, which without this filter would spawn a post_by_email_address option
3. Do wp option list --search="post_by_email*" --fields=option_name,option_value,autoload
4. Verify that no new post_by_email_address option has been created for your logged-in user ID
5. To verify that non-NULL post_by_email_address* options aren't filtered, add this quick snippet to a sandbox and redo steps 2 & 3:

function create_post_by_email_option()
{
    $current_user_id = get_current_user_id();
    $option_name = 'post_by_email_address' . $current_user_id;
    update_option($option_name, 'NOTNULL');
}

add_action('admin_init', 'create_post_by_email_option');

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 28.95%. Comparing base (d51ee58) to head (9f9eacd).
Report is 1 commits behind head on develop.

Files	Patch %	Lines
vip-jetpack/vip-jetpack.php	0.00%	10 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #5311      +/-   ##
=============================================
- Coverage      29.03%   28.95%   -0.09%     
  Complexity      4822     4822              
=============================================
  Files            283      283              
  Lines          20927    20925       -2     
=============================================
- Hits            6077     6059      -18     
- Misses         14850    14866      +16     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud