Revert "Introduce a Hashing Processor (#31087)" (#32178)

This reverts commit 8c78fe7.

x-pack/plugin/build.gradle

@@ -151,7 +151,6 @@ integTestCluster {
   setting 'xpack.license.self_generated.type', 'trial'
   keystoreSetting 'bootstrap.password', 'x-pack-test-password'
   keystoreSetting 'xpack.security.transport.ssl.keystore.secure_password', 'keypass'
-  keystoreSetting 'xpack.security.ingest.hash.processor.key', 'hmackey'
   distribution = 'zip' // this is important since we use the reindex module in ML
 
   setupCommand 'setupTestUser', 'bin/elasticsearch-users', 'useradd', 'x_pack_rest_user', '-p', 'x-pack-test-password', '-r', 'superuser'

x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/Security.java

@@ -175,7 +175,6 @@
 import org.elasticsearch.xpack.security.authz.store.CompositeRolesStore;
 import org.elasticsearch.xpack.security.authz.store.FileRolesStore;
 import org.elasticsearch.xpack.security.authz.store.NativeRolesStore;
-import org.elasticsearch.xpack.security.ingest.HashProcessor;
 import org.elasticsearch.xpack.security.ingest.SetSecurityUserProcessor;
 import org.elasticsearch.xpack.security.rest.SecurityRestFilter;
 import org.elasticsearch.xpack.security.rest.action.RestAuthenticateAction;
@@ -580,10 +579,6 @@ public static List<Setting<?>> getSettings(boolean transportClientMode, List<Sec
         // hide settings
         settingsList.add(Setting.listSetting(SecurityField.setting("hide_settings"), Collections.emptyList(), Function.identity(),
                 Property.NodeScope, Property.Filtered));
-
-        // ingest processor settings
-        settingsList.add(HashProcessor.HMAC_KEY_SETTING);
-
         return settingsList;
     }
 
@@ -727,10 +722,7 @@ public List<RestHandler> getRestHandlers(Settings settings, RestController restC
 
     @Override
     public Map<String, Processor.Factory> getProcessors(Processor.Parameters parameters) {
-        Map<String, Processor.Factory> processors = new HashMap<>();
-        processors.put(SetSecurityUserProcessor.TYPE, new SetSecurityUserProcessor.Factory(parameters.threadContext));
-        processors.put(HashProcessor.TYPE, new HashProcessor.Factory(parameters.env.settings()));
-        return processors;
+        return Collections.singletonMap(SetSecurityUserProcessor.TYPE, new SetSecurityUserProcessor.Factory(parameters.threadContext));
     }