Add woo install timestamp to server experimental assignment requests

[joshuatf]

All Submissions:

• Have you followed the WooCommerce Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Closes (part of) #33295 .

How to test the changes in this Pull Request:

1. Create a new site
2. Add this as a plugin:

add_filter( 'pre_http_request', function( $bool, $parsed_args, $url ) {
	$logger = wc_get_logger();
	$logger->debug( $url );
	$logger->debug(
		$url,
		array( 'source' => 'experiments' )
	);
	return $bool;
}, 10, 3 );

3. Visit the homepage
4. Visit the logs page wp-admin/admin.php?page=wc-status&tab=logs
5. Check the experiments-* log
6. See that woo_wcadmin_install_timestamp is in the URL with the correct timestamp

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully run tests with your changes locally?
• Have you created a changelog file for each project being changed, ie pnpm nx changelog <project>?

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.

[botwoo]

📊 Test reports for this pull request have been published and are accessible through the following links:

• REST API Test Report
• E2E Test Report (TBC)

Latest commit referenced in the reports: Add changelog entry d87cccb
This comment will automatically be updated with the latest referenced commit when you push new changes to this pull request.

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[louwie17]

LGTM 🚀 Tested well, thanks for adding this, I seem to get assigned an experiment on Jurassic :)

[louwie17]

LGTM 🚀

[github-actions]

Hi @joshuatf, thanks for merging this pull request. Please take a look at these follow-up tasks you may need to perform:

• Add the release: add testing instructions label

[jonathansadowski]

This has been cherry-picked into the 6.6 release branch