fix(collection): catch RuntimeException from removed /admin/mbeans in Solr 10

SolrInfoMBeanHandler (and thus the /admin/mbeans endpoint) was removed in
Solr 10. When getCacheMetrics() or getHandlerMetrics() call this endpoint on
a Solr 10 server, SolrJ throws RemoteSolrException (a RuntimeException) because
the server returns an HTML 404 page instead of JSON.

Widen the catch in both methods to include RuntimeException so the server
degrades gracefully (returning null for cache/handler stats) rather than
propagating the exception. The integration tests already handle null stats,
so all tests now pass with solr:10-slim.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: adityamparikh <aditya.m.parikh@gmail.com>

Author: adityamparikh

src/main/java/org/apache/solr/mcp/server/metadata/CollectionService.java

@@ -609,7 +609,9 @@ public CacheStats getCacheMetrics(String collection) {
 			}
 
 			return stats;
-		} catch (SolrServerException | IOException e) {
+		} catch (SolrServerException | IOException | RuntimeException e) {
+			// RuntimeException covers SolrException subclasses (e.g. RemoteSolrException)
+			// thrown when the /admin/mbeans endpoint is unavailable (removed in Solr 10).
 			return null; // Return null instead of empty object
 		}
 	}
@@ -781,7 +783,9 @@ public HandlerStats getHandlerMetrics(String collection) {
 			}
 
 			return stats;
-		} catch (SolrServerException | IOException e) {
+		} catch (SolrServerException | IOException | RuntimeException e) {
+			// RuntimeException covers SolrException subclasses (e.g. RemoteSolrException)
+			// thrown when the /admin/mbeans endpoint is unavailable (removed in Solr 10).
 			return null; // Return null instead of empty object
 		}
 	}