(NFC) JSTest - Speed up ~60%

Before: On local i3-12100, takes ~34s (avg over two runs)

After: On local i3-12100, take ~14s (avg over two runs)

tests/phpunit/CRM/Utils/JSTest.php

@@ -15,6 +15,14 @@
  */
 class CRM_Utils_JSTest extends CiviUnitTestCase {
 
+  /**
+   * Set up for tests.
+   */
+  public function setUp(): void {
+    $this->useTransaction();
+    parent::setUp();
+  }
+
   /**
    * @return array
    */