The `executionStats` and `allPlanExecution` explain output for stages that can spill now include the following fields:
spills: The number of times the stage spilled to disk.
spilledBytes: The total amount of data spilled to disk in bytes.
spilledRecords: The total number of records spilled to disk.
spilledDataStorageSize: The total disk space used by spilled data in bytes.
The previous fields that reported this information have been replaced by these new fields. Specifically:
`spilledBytesApprox` is now `spilledBytes` in `$lookup` and `$lookup-unwind` stages.
`numBytesSpilledEstimate` is now `spilledBytes` in `$group` and `$setWindowFields` stages.

Description of Linked Ticket

Currently a lot of stages can spill to disk, but in explain output they will report different sub-set of spilling statistics under different names:

DocumentSourceGroup will report spilled bytes as numBytesSpilledEstimate

DocumentSourceGraphLookup will report it as spilledBytes.

DocumentSourceSort won't even report this metric

In SERVER-99564 we will ensure that all spilling stages track internally all relevant metrics consistently.

In this ticket we should make the change to explain output to be consistent as well.