simplify answers handling

examples/answers.yaml

@@ -18,7 +18,6 @@ Identity:
   # ubuntu
   password: '$6$wdAcoXrU039hKYPd$508Qvbe7ObUnxoj15DRCkzC3qO7edjH0VV7BPNRDYK4QR8ofJaEEF2heacn0QgD.f8pO8SNp83XNdWG6tocBM1'
   ssh_import_id: lp:mwhudson
-  accept-ssh-key: true
 InstallProgress:
   reboot: yes
 

subiquity/controllers/identity.py

@@ -89,7 +89,7 @@ class IdentityController(BaseController):
             ok, rest = result[0], result[1:]
             if ok:
                 result, key_material, fingerprints = rest
-                if self.answers.get('accept-ssh-key'):
+                if 'ssh_import_id' in self.answers:
                     result['ssh_keys'] = key_material.splitlines()
                     self.loop.set_alarm_in(0.0, lambda loop, ud: self.done(result))
                 else: