Allow LimitOperator in Driver assertion (elastic#130235)

The LimitOperator can be finished early because the Limiter may be 
shared across operators. This PR relaxes the assertion to allow for
this.

Closes elastic#130228
Closes elastic#130219

Author: dnhatn

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/operator/Driver.java

@@ -267,7 +267,7 @@ private IsBlockedResult runSingleLoopIteration() {
 
             if (op.isFinished() == false && nextOp.needsInput()) {
                 driverContext.checkForEarlyTermination();
-                assert nextOp.isFinished() == false || nextOp instanceof ExchangeSinkOperator
+                assert nextOp.isFinished() == false || nextOp instanceof ExchangeSinkOperator || nextOp instanceof LimitOperator
                     : "next operator should not be finished yet: " + nextOp;
                 Page page = op.getOutput();
                 if (page == null) {