Enable concurrent profiling

Concurrent search execution has been disabled so far whenever profile is on. In practice,
there are scenarios for which we can't really disable concurrency, because concurrency is
not always based on slices. That makes it more important to address the concurrency issues
in the profiler and enable concurrent profiling across the board.

server/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -2172,12 +2172,12 @@ public String toString(Params params) {
     }
 
     public boolean supportsParallelCollection(ToLongFunction<String> fieldCardinality) {
-        if (profile) return false;
-
         if (sorts != null) {
             // the implicit sorting is by _score, which supports parallel collection
             for (SortBuilder<?> sortBuilder : sorts) {
-                if (sortBuilder.supportsParallelCollection() == false) return false;
+                if (sortBuilder.supportsParallelCollection() == false) {
+                    return false;
+                }
             }
         }