engine: Removing canDoaction from ConnectHostToStoragePoolServersCommand

The following change is removes canDoAction from ConnectHostToStoragePoolServersCommand.
The purpose of canDoAction was to validate storage connections at VDSM, the following API
is depreacted and not useful at vdsm side, and doesn't provide any benefit to engine, also
the following command is internal so no reason to perfrom additional xml rpc call in order to
validate storage server connection.
Benefit, reduced number of XML RPC calls via InitVdsOnUp, meaning vds should be moved to status UP
much faster.
Additional benefit, less code, less bugs

Change-Id: I0124e47b2f1194e5de9b40216cd285c47b1b6f94
Signed-off-by: Michael Kublin <mkublin@redhat.com>