[CX] Graphical explain plan broken

As a result of MB-54096, we add cardinality and cost information to the JSON explain plan as shown below:

Specifically, we add the following to the EXPLAIN plan.

estimated per-operator cardinality
estimated per-operator cost
estimated total cost for the plan up to the current operator
estimated cardinality for the whole plan
estimated total cost for the whole plan

Example snippet of query plan:

"requestID": "01af0e04-c950-4f6d-878b-05cd4c43c5a0",
"signature":

{ "*": "*" }

,
"results": [ {
*"cardinality" : 15.0,
"cost" : 5021.1,
"plan" : {*
"operator" : "distribute-result",
"expressions" : [
"$$36"
],
"operatorId" : "1.1",
"runtime-id" : "ODID:1",
"physical-operator" : "DISTRIBUTE_RESULT",
"execution-mode" : "UNPARTITIONED",
"optimizer-estimates" :

{ "cardinality" : 15.0, "op-cost" : 0.0, "total-cost" : 5021.1 }

,
"inputs" : [
{
"operator" : "exchange",
"operatorId" : "1.2",
"runtime-id" : "CDID:3",
"physical-operator" : "ONE_TO_ONE_EXCHANGE",
"execution-mode" : "UNPARTITIONED",
"optimizer-estimates" :

{ "cardinality" : 15.0, "op-cost" : 0.0, "total-cost" : 5021.1 }

,

As a result, the plan is now embedded inside the results.plan field, which the GUI is not expecting and we do not get a graphical explain plan.