Revert "LYNX-455: Make sure cookie name in assertion ends with '=' to avoid cookie name collision (#262)"

This reverts commit 27fead0.

Author: svera

dev/tests/api-functional/testsuite/Magento/GraphQl/PageCache/DisableSessionTest.php

@@ -77,7 +77,7 @@ public function testPrivateSessionContentCookiePresentWhenSessionEnabled()
     private function isCookieSet(array $setCookieHeader, string $cookieName): bool
     {
         return count(array_filter($setCookieHeader, function ($cookie) use ($cookieName) {
-            return str_starts_with($cookie, $cookieName . '=');
+            return str_starts_with($cookie, $cookieName);
         })) > 0;
     }