Ensure keywords string does not exceed database field length

The keywords field of the statistics database is only 128 characters
long. If a search keyword with more than 128 chars is used, the 
database insert fails if statistics are enabled.

Fixes: TYPO3-Solr#3321
Ports: TYPO3-Solr#3322

Classes/Domain/Search/Statistics/StatisticsWriterProcessor.php

@@ -123,6 +123,8 @@ protected function getProcessedKeywords(
     ): string {
         $keywords = $query->getQuery();
         $keywords = $this->sanitizeString($keywords);
+        // Ensure string does not exceed database field length
+        $keywords = substr($keywords, 0, 128);
         if ($lowerCaseQuery) {
             $keywords = mb_strtolower($keywords);
         }