Use mcdsl/terminal for all password prompts

Replace direct golang.org/x/term calls with mcdsl/terminal.ReadPassword
across mciasctl (6 sites), mciasgrpcctl (1 site), and mciasdb (1 site).
Aligns with the new CLI security standard in engineering-standards.md.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/google.golang.org/grpc/balancer/subconn.go

@@ -111,20 +111,6 @@ type SubConnState struct {
 	// ConnectionError is set if the ConnectivityState is TransientFailure,
 	// describing the reason the SubConn failed.  Otherwise, it is nil.
 	ConnectionError error
-	// connectedAddr contains the connected address when ConnectivityState is
-	// Ready. Otherwise, it is indeterminate.
-	connectedAddress resolver.Address
-}
-
-// connectedAddress returns the connected address for a SubConnState. The
-// address is only valid if the state is READY.
-func connectedAddress(scs SubConnState) resolver.Address {
-	return scs.connectedAddress
-}
-
-// setConnectedAddress sets the connected address for a SubConnState.
-func setConnectedAddress(scs *SubConnState, addr resolver.Address) {
-	scs.connectedAddress = addr
 }
 
 // A Producer is a type shared among potentially many consumers.  It is