bugfix: reduce enum array allocation in QueryLogger (#12478)

Motivation:

reduce enum array allocation in QueryLogger

Modifications:

cache QueryLogEntry.values() in a static variable

Result:

Java enum .values() method is invoked exactly once

Additional context:

https://www.gamlor.info/wordpress/2017/08/javas-enum-values-hidden-allocations/

pinot-broker/src/main/java/org/apache/pinot/broker/querylog/QueryLogger.java

@@ -45,6 +45,7 @@
 public class QueryLogger {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(QueryLogger.class);
+  private static final QueryLogEntry[] QUERY_LOG_ENTRY_VALUES = QueryLogEntry.values();
 
   private final int _maxQueryLengthToLog;
   private final RateLimiter _logRateLimiter;
@@ -82,7 +83,7 @@ public void log(QueryLogParams params) {
     }
 
     final StringBuilder queryLogBuilder = new StringBuilder();
-    for (QueryLogEntry value : QueryLogEntry.values()) {
+    for (QueryLogEntry value : QUERY_LOG_ENTRY_VALUES) {
       value.format(queryLogBuilder, this, params);
       queryLogBuilder.append(',');
     }