A disconnected media server still showed up in Compare servers

A repair to 0.35.0: a disconnected media server no longer appears in the comparison table.

Fixed

• A disconnected media server still showed up in Compare servers. Its library stayed in the database after disconnecting, so the table showed it as a column with its old state, and everything that had changed since counted as a difference. The comparison and the reconciliation findings now only count connected servers. Disconnecting removes that server's library, and the next sync clears what earlier versions left behind.