[BUGFIX] Fix RTE file links migration

Links in RTE might be stored as <LINK or <link.
Currently the upgrade wizards lacks support for <LINK.
Add this to the regular expression.

Resolves: #51800
Releases: 6.3, 6.2
Change-Id: Ic22983db1144fb1317d6102907c792871e1eeaed
Reviewed-on: https://review.typo3.org/30820
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Alexander Opitz
Tested-by: Alexander Opitz
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters

typo3/sysext/install/Classes/Updates/RteFileLinksUpdateWizard.php

@@ -204,7 +204,7 @@ class RteFileLinksUpdateWizard extends AbstractUpdate {
 		if ($fileObject instanceof \TYPO3\CMS\Core\Resource\AbstractFile) {
 			// Next, match the reference path in the content to be sure it's present inside a <link> tag
 			$content = $record[$reference['field']];
-			$regularExpression = '$<(link ' . str_replace(' ', '%20', $reference['ref_string']) . ').*>$';
+			$regularExpression = '$<((link|LINK) ' . str_replace(' ', '%20', $reference['ref_string']) . ').*>$';
 			$matches = array();
 			$result = preg_match($regularExpression, $content, $matches);
 			if ($result) {