[native] fix regression in error handling
Summary:
if the password is wrong we shouldn't display the unknown error text.
Improving the error message is tracked in https://linear.app/comm/issue/ENG-7111/make-grpc-statuses-clearer-in-protocol-error-to-grpc-status-function
Test Plan: confirmed that the "incorrect username or password" alert displays now when the password is incorrect
Reviewers: ashoat
Reviewed By: ashoat
Subscribers: tomek
Differential Revision: https://phab.comm.dev/D11514