-keep_data is ignored in v2 vreplication workflows

[ajm188]

Overview of the Issue

The v2 workflows have swapped the -force and -keep_data arguments passed to wr.DropSources meaning that in order to keep data, you need to pass -force, and in order to force, you need to pass -keep_data.

v1 method call: wr.DropSources(ctx, keyspace, workflowName, removalType, *keepData, false, *dryRun)
v2 method call: wr.DropSources(vrw.ctx, vrw.ws.TargetKeyspace, vrw.ws.Workflow, renameTable, false, vrw.params.KeepData, vrw.params.DryRun)

Reproduction Steps

vtctlclient -server "$server" Reshard -v2 -dry_run -keep_data Complete "mykeyspace.reshard"
Dry Run results for 02 Jan 06 15:04 MST run at Complete
Parameters: -v2 -dry_run -keep_data Complete mykeyspace.reshard

Lock keyspace mykeyspace
Deleting following shards (and all related tablets):
		[tablet aliases omitted]
	Cell mycell Keyspace mykeyspace Shard
$shard
Delete reverse vreplication streams on source:
[more output deleting streams, etc]

Binary version

We're experiencing this in 10.0, but git history suggests that this is still an issue in main, and therefore probably also 11.0 and 12.0.