To avoid ambiguity (as cluster and index policies may have the same

name) changing implementation to have to separate policies for
`index_privileges` and `cluster_privileges`.
If both are set for the same policy, throw the IllegalArgumentException.

Author: BigPandaToo

x-pack/plugin/security/src/internalClusterTest/java/org/elasticsearch/xpack/security/audit/logfile/AuditTrailSettingsUpdateTests.java

@@ -96,7 +96,7 @@ public void testInvalidFilterSettings() throws Exception {
                 "xpack.security.audit.logfile.events.ignore_filters.invalid.realms",
                 "xpack.security.audit.logfile.events.ignore_filters.invalid.roles",
                 "xpack.security.audit.logfile.events.ignore_filters.invalid.indices",
-                "xpack.security.audit.logfile.events.ignore_filters.invalid.privileges"};
+                "xpack.security.audit.logfile.events.ignore_filters.invalid.index_privileges"};
         settingsBuilder.put(randomFrom(allSettingsKeys), invalidLuceneRegex);
         final IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
                 () -> client().admin().cluster().prepareUpdateSettings().setTransientSettings(settingsBuilder.build()).get());
@@ -226,7 +226,7 @@ private static Settings randomFilterPolicySettings(String policyName) {
             if (randomBoolean()) {
                 // filter by privileges
                 final List<String> filteredPrivileges = randomNonEmptyListOfFilteredNames();
-                settingsBuilder.putList("xpack.security.audit.logfile.events.ignore_filters." + policyName + ".privileges",
+                settingsBuilder.putList("xpack.security.audit.logfile.events.ignore_filters." + policyName + ".index_privileges",
                     filteredPrivileges);
             }
         } while (settingsBuilder.build().isEmpty());