Unmute kerberos tests for jdk 15 and mute for jdk 8u262 (elastic#60279)

The JDK bug (https://bugs.openjdk.java.net/browse/JDK-8246193) is fixed since b26.
The tests can be unmuted since we are already using b33. However the same bug is now
affecting jdk 8u262, which is the base for current Zulu jdk 8.48. This PR mute the tests
for this specific jdk version.

Relates: elastic#56507

x-pack/qa/kerberos-tests/src/test/java/org/elasticsearch/xpack/security/authc/kerberos/KerberosAuthenticationIT.java

@@ -8,7 +8,6 @@
 
 import org.apache.http.HttpEntity;
 import org.apache.http.HttpHost;
-import org.elasticsearch.bootstrap.JavaVersion;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.Response;
 import org.elasticsearch.client.RestClient;
@@ -90,13 +89,13 @@ public void setupRoleMapping() throws IOException {
         assertOK(response);
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/56507")
-    public void testSuppressedOnJDK15() {
-        assumeTrue("AwaitsFix on JDK15", JavaVersion.current().compareTo(JavaVersion.parse("15")) < 0);
+    //  JDK 8u262 shipped with a NPE in Kerberos code, see https://github.com/elastic/elasticsearch/issues/56507
+    public void testSuppressedOnJDK8u262() {
+        assumeFalse("Cannot run on JDK 8u262", "1.8.0_262".equals(System.getProperty("java.version")));
     }
 
     public void testLoginByKeytab() throws IOException, PrivilegedActionException {
-        testSuppressedOnJDK15();
+        testSuppressedOnJDK8u262();
         final String userPrincipalName = System.getProperty(TEST_USER_WITH_KEYTAB_KEY);
         final String keytabPath = System.getProperty(TEST_USER_WITH_KEYTAB_PATH_KEY);
         final boolean enabledDebugLogs = Boolean.parseBoolean(System.getProperty(ENABLE_KERBEROS_DEBUG_LOGS_KEY));
@@ -106,7 +105,7 @@ public void testLoginByKeytab() throws IOException, PrivilegedActionException {
     }
 
     public void testLoginByUsernamePassword() throws IOException, PrivilegedActionException {
-        testSuppressedOnJDK15();
+        testSuppressedOnJDK8u262();
         final String userPrincipalName = System.getProperty(TEST_USER_WITH_PWD_KEY);
         final String password = System.getProperty(TEST_USER_WITH_PWD_PASSWD_KEY);
         final boolean enabledDebugLogs = Boolean.parseBoolean(System.getProperty(ENABLE_KERBEROS_DEBUG_LOGS_KEY));
@@ -116,7 +115,7 @@ public void testLoginByUsernamePassword() throws IOException, PrivilegedActionEx
     }
 
     public void testGetOauth2TokenInExchangeForKerberosTickets() throws PrivilegedActionException, GSSException, IOException {
-        testSuppressedOnJDK15();
+        testSuppressedOnJDK8u262();
         final String userPrincipalName = System.getProperty(TEST_USER_WITH_PWD_KEY);
         final String password = System.getProperty(TEST_USER_WITH_PWD_PASSWD_KEY);
         final boolean enabledDebugLogs = Boolean.parseBoolean(System.getProperty(ENABLE_KERBEROS_DEBUG_LOGS_KEY));