chore(java-shell): skip executionStats validation in tests (#873)

The SBE engine has been turned on by default in the latest server
versions, which returns a different explain output in executionStats.
Therefore, skip validation in the java-shell tests, which currently
expect the pre-5.0 format.

Author: addaleax

packages/java-shell/src/test/resources/cursor/explain.expected.txt

@@ -3,6 +3,3 @@
 "admin.coll"
 true
 false
-42
-{ "name": { "$eq": "Vasya" } }
-{ "_id": -1 }

packages/java-shell/src/test/resources/cursor/explain.js

@@ -13,11 +13,5 @@ db.coll.find().explain();
 db.coll.find().explain("executionStats");
 // command containsProperty=executionStats
 db.coll.find().explain("queryPlanner");
-// command extractProperty=executionStats extractProperty=executionStages extractProperty=limitAmount
-db.coll.find().limit(42).explain("executionStats");
-// command extractProperty=executionStats extractProperty=executionStages extractProperty=filter
-db.coll.find({name: "Vasya"}).explain("executionStats");
-// command extractProperty=executionStats extractProperty=executionStages extractProperty=transformBy
-db.coll.find({}, {_id: -1}).explain("executionStats");
 // clear
-db.coll.drop();
+db.coll.drop();