Add hold invoice status for lnd to xud-docker status response

[raladev]

[kilrau]

No idea how these kind of things are regressing, we clearly defined: if (lndbtc status == ready) set status = ready else show whatever message the lndbtc status field contains in status

[kilrau]

Shouldn't be a complicated fix, can you take this on when you want to distract yourself for some minutes? @reliveyy