Revert "Upgrade to Solr 9.0.0"

It requires Jetty 9.4.x but we're using Jetty 11.

This reverts commit b2bd3dee5e.

See gh-31054

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/solr/SolrAutoConfiguration.java

@@ -21,7 +21,7 @@ import java.util.Optional;
 
 import org.apache.solr.client.solrj.SolrClient;
 import org.apache.solr.client.solrj.impl.CloudSolrClient;
-import org.apache.solr.client.solrj.impl.Http2SolrClient;
+import org.apache.solr.client.solrj.impl.HttpSolrClient;
 
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
@@ -38,7 +38,7 @@ import org.springframework.util.StringUtils;
  * @since 1.1.0
  */
 @AutoConfiguration
-@ConditionalOnClass({ Http2SolrClient.class, CloudSolrClient.class })
+@ConditionalOnClass({ HttpSolrClient.class, CloudSolrClient.class })
 @EnableConfigurationProperties(SolrProperties.class)
 public class SolrAutoConfiguration {
 
@@ -48,7 +48,7 @@ public class SolrAutoConfiguration {
 		if (StringUtils.hasText(properties.getZkHost())) {
 			return new CloudSolrClient.Builder(Arrays.asList(properties.getZkHost()), Optional.empty()).build();
 		}
-		return new Http2SolrClient.Builder(properties.getHost()).build();
+		return new HttpSolrClient.Builder(properties.getHost()).build();
 	}
 
 }

spring-boot-project/spring-boot-dependencies/build.gradle

@@ -1357,27 +1357,26 @@ bom {
 			]
 		}
 	}
-	library("Solr", "9.0.0") {
+	library("Solr", "8.11.1") {
 		group("org.apache.solr") {
 			modules = [
 				"solr-analysis-extras",
 				"solr-analytics",
+				"solr-cell",
 				"solr-core",
-				"solr-extraction",
+				"solr-dataimporthandler",
+				"solr-dataimporthandler-extras",
 				"solr-gcs-repository",
-				"solr-hadoop-auth",
-				"solr-hdfs",
 				"solr-jaegertracer-configurator",
-				"solr-jwt-auth",
 				"solr-langid",
 				"solr-ltr",
 				"solr-prometheus-exporter",
 				"solr-s3-repository",
-				"solr-scripting",
 				"solr-solrj" {
 					exclude group: "org.slf4j", module: "jcl-over-slf4j"
 				},
-				"solr-test-framework"
+				"solr-test-framework",
+				"solr-velocity"
 			]
 		}
 	}