refactor(doctor): remove ionic doctor command (#4959)

BREAKING CHANGE:

The `ionic doctor` command has been removed. See #4907 for alternatives.

Author: liamdebeasi

packages/@ionic/cli/src/__tests__/guards.ts

@@ -38,7 +38,6 @@ const OBJECT_GUARDS: Guard[] = [
   guards.isSSHKeyResponse,
   guards.isSecurityProfile,
   guards.isSecurityProfileResponse,
-  guards.isTreatableAilment,
   guards.isIntegrationName,
   guards.isProjectConfig,
   guards.isMultiProjectConfig,