Remove ignored fallback option on GeoIP processor (#116112)

This removes the option `fallback_to_default_databases` on the `geoip`
ingest processor has been deprecated and ignored since 8.0.0.

Author: PeteGillinElastic

docs/changelog/116112.yaml

@@ -0,0 +1,13 @@
+pr: 116112
+summary: Remove ignored fallback option on GeoIP processor
+area: Ingest Node
+type: breaking
+issues: []
+breaking:
+  title: Remove ignored fallback option on GeoIP processor
+  area: Ingest
+  details: >-
+    The option fallback_to_default_databases on the geoip ingest processor has been removed.
+    (It was deprecated and ignored since 8.0.0.)
+  impact: Customers should stop remove the noop fallback_to_default_databases option on any geoip ingest processors.
+  notable: false

modules/ingest-geoip/src/main/java/org/elasticsearch/ingest/geoip/GeoIpProcessor.java

@@ -36,8 +36,6 @@
 public final class GeoIpProcessor extends AbstractProcessor {
 
     private static final DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(GeoIpProcessor.class);
-    static final String DEFAULT_DATABASES_DEPRECATION_MESSAGE = "the [fallback_to_default_databases] has been deprecated, because "
-        + "Elasticsearch no longer includes the default Maxmind geoip databases. This setting will be removed in Elasticsearch 9.0";
     static final String UNSUPPORTED_DATABASE_DEPRECATION_MESSAGE = "the geoip processor will no longer support database type [{}] "
         + "in a future version of Elasticsearch"; // TODO add a message about migration?
 
@@ -241,12 +239,6 @@ public Processor create(
             // validate (and consume) the download_database_on_pipeline_creation property even though the result is not used by the factory
             readBooleanProperty(type, processorTag, config, "download_database_on_pipeline_creation", true);
 
-            // noop, should be removed in 9.0
-            Object value = config.remove("fallback_to_default_databases");
-            if (value != null) {
-                deprecationLogger.warn(DeprecationCategory.OTHER, "default_databases_message", DEFAULT_DATABASES_DEPRECATION_MESSAGE);
-            }
-
             final String databaseType;
             try (IpDatabase ipDatabase = ipDatabaseProvider.getDatabase(databaseFile)) {
                 if (ipDatabase == null) {

modules/ingest-geoip/src/test/java/org/elasticsearch/ingest/geoip/GeoIpProcessorFactoryTests.java

@@ -473,15 +473,6 @@ public void testLoadingCustomDatabase() throws IOException {
         threadPool.shutdown();
     }
 
-    public void testFallbackUsingDefaultDatabases() throws Exception {
-        GeoIpProcessor.Factory factory = new GeoIpProcessor.Factory(GEOIP_TYPE, databaseNodeService);
-        Map<String, Object> config = new HashMap<>();
-        config.put("field", "source_field");
-        config.put("fallback_to_default_databases", randomBoolean());
-        factory.create(null, null, null, config);
-        assertWarnings(GeoIpProcessor.DEFAULT_DATABASES_DEPRECATION_MESSAGE);
-    }
-
     public void testDownloadDatabaseOnPipelineCreation() throws IOException {
         GeoIpProcessor.Factory factory = new GeoIpProcessor.Factory(GEOIP_TYPE, databaseNodeService);
         Map<String, Object> config = new HashMap<>();