hw: rm dead code from Hardware_KeyStore subclasses

- force_watching_only is long since unused
- comment was just duplicated from the base class

electrum/plugins/bitbox02/bitbox02.py

@@ -559,7 +559,6 @@ class BitBox02_KeyStore(Hardware_KeyStore):
 
     def __init__(self, d: dict):
         super().__init__(d)
-        self.force_watching_only = False
         self.ux_busy = False
 
     def get_client(self) -> Optional['BitBox02Client']:

electrum/plugins/coldcard/coldcard.py

@@ -251,10 +251,6 @@ class Coldcard_KeyStore(Hardware_KeyStore):
 
     def __init__(self, d):
         Hardware_KeyStore.__init__(self, d)
-        # Errors and other user interaction is done through the wallet's
-        # handler.  The handler is per-window and preserved across
-        # device reconnects
-        self.force_watching_only = False
         self.ux_busy = False
 
         # we need to know at least the fingerprint of the master xpub to verify against MiTM

electrum/plugins/digitalbitbox/digitalbitbox.py

@@ -442,7 +442,6 @@ class DigitalBitbox_KeyStore(Hardware_KeyStore):
 
     def __init__(self, d):
         Hardware_KeyStore.__init__(self, d)
-        self.force_watching_only = False
         self.maxInputs = 14 # maximum inputs per single sign command
 
     def give_error(self, message, clear_client = False):

electrum/plugins/ledger/ledger.py

@@ -246,10 +246,6 @@ class Ledger_KeyStore(Hardware_KeyStore):
 
     def __init__(self, d):
         Hardware_KeyStore.__init__(self, d)
-        # Errors and other user interaction is done through the wallet's
-        # handler.  The handler is per-window and preserved across
-        # device reconnects
-        self.force_watching_only = False
         self.signing = False
         self.cfg = d.get('cfg', {'mode': 0})