StorageService: Add the scrub 3.11 command implementation

[amnonh]

The scrub command was not supported from node_tool, but now when we want to enable it the current API is not compatible with the 3.11 MBean definition.

This patch adds the definition to the MBean and the implementation to StorageService.

It also addresses two problems with the old scrub implementation, just in case someone will use them.

1. Implementation didn't pass the parameters to the API.
2. A stub implementation called itself instead of calling an actual implementation.

This patch will enable to test the command from nodetool additional changes may come on top of it if more command line options will be supported.

Relates to scylladb/scylla#6072

Signed-off-by: Amnon Heiman amnon@scylladb.com

[slivne]

@penberg ping

[slivne]

@penberg ping

[slivne]

@penberg ping