Fix name of solr health indicator

Fixes gh-2410

Author: snicoll

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/HealthIndicatorAutoConfiguration.java

@@ -215,7 +215,7 @@ public static class SolrHealthIndicatorConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean(name = "solrHealthIndicator")
-		public HealthIndicator rabbitHealthIndicator() {
+		public HealthIndicator solrHealthIndicator() {
 			if (this.solrServers.size() == 1) {
 				return new SolrHealthIndicator(this.solrServers.entrySet().iterator()
 						.next().getValue());