dbDelta returns unnecessary update if tablename is in backticks

[leewillis77]

If the SQL passed to dbDelta has backticks around the tablename, then dbDelta will always return an update implying that the table will be created, even if it already exists and no changes are required.

E.g. the following code:

<?php

require_once ABSPATH . 'wp-admin/includes/upgrade.php';
$for_update = dbDelta('CREATE TABLE `foo` (id INT)');

will always return the following array, even when the table exists and no changes are required:

[`foo`] => Created table `foo`

Patch to follow

This change ensures that dbDelta does not erroneously return an apparent update to tables when the tablename contains backticks.

Trac ticket: https://core.trac.wordpress.org/ticket/63976

[swissspidy]

Tip: adding a PR is enough, no need to upload a patch file as well :-)

[johnbillion]

Related: #59481

[SergeyBiryukov]

In 60782:

Database: Do not report an extra update in dbDelta() with backticks in table name.

Follow-up to [10948], [20704].

Props leewillis77, swissspidy, johnbillion, SergeyBiryukov.
Fixes #63976.