SERVER-73120 removed the recordRemoteOpWaitTime field from src/mongo/s/query/exec/async_results_merger_params.idl.

This field did not have any meaning since SERVER-46446 was merged (6.2), but it will still appear with its default value false in the serialized outputs of every $mergeCursors stage in versions < 9.0.

Removing the field from the IDL leads to any serialized $mergeCursors stage definition from versions < 9.0 to be unparseable in 9.0 and higher. To avoid compatibility problems in upgrade scenarios/mixed version clusters, SERVER-73120 adds a compatibility check that makes the parsing work even if the field is still present in the input BSON.

This ensures compatibility with older versions, but allows us to remove the field from the IDL for v9.0.

The compatibility check can be removed once v9.0 becomes last LTS.