make elasticsearch provider optional if search.elasticsearch not defined

Signed-off-by: Andrew Ochsner <andrew.ochsner@cognizant.com>

.changeset/tough-snakes-wink.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-search-backend-module-elasticsearch': minor
+---
+
+For new backend, make Elasticsearch provider optional if no config

plugins/search-backend-module-elasticsearch/src/alpha.ts

@@ -68,6 +68,12 @@ export default createBackendModule({
         config: coreServices.rootConfig,
       },
       async init({ searchEngineRegistry, logger, config }) {
+        const baseKey = 'search.elasticsearch';
+        const baseConfig = config.getOptional(baseKey);
+        if (!baseConfig) {
+          return;
+        }
+
         searchEngineRegistry.setSearchEngine(
           await ElasticSearchSearchEngine.fromConfig({
             logger,