Tests: Correct the tests for Site Health SQL versions matching `readme.html`.

These tests should check the initial `$mysql_recommended_version` and `$mariadb_recommended_version` properties, as `WP_Site_Health::prepare_sql_data()` redefines the former with the latter to simplify further processing if MariaDB is used, leading to a test failure:
{{{
Tests_Site_Health::test_mysql_recommended_version_matches_readme_html
Failed asserting that two strings are identical.
--- Expected
+++ Actual
@@ @@
-'5.7'
+'10.3'
}}}

This commit uses the initial property values to ensure the correct versions are being compared.

Follow-up to [54069].

See #55791.
Built from https://develop.svn.wordpress.org/trunk@54076


git-svn-id: http://core.svn.wordpress.org/trunk@53635 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.1-alpha-54075';
+$wp_version = '6.1-alpha-54076';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.