$allowed_constants is not defined in class-wp-site-health-auto-updates.php

[diddledani]

In the file wp-admin/includes/class-wp-site-health-auto-updates.php line 69 a test is made against the variable $allowed_constants which is guaranteed to be undefined because it is not set within the function nor is it pulled via global. This is the only reference within the entire WordPress source code to a variable with this name, so even if we add global it will still be undefined unless a plugin or theme defines it.

https://core.trac.wordpress.org/browser/trunk/src/wp-admin/includes/class-wp-site-health-auto-updates.php#L69

[SergeyBiryukov]

In 45223:

Site Health: Remove reference to an undefined variable in WP_Site_Health_Auto_Updates::test_constants().

Props diddledan.
Fixes #46952.