[native] regenerate backup on every password change

Summary:
ENG-8070

Some concerns are listed the comment in ENG-8070.

Depends on D14063

Test Plan: On primary device, change password and check that new backup was uploaded

Reviewers: bartek, tomek

Reviewed By: bartek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D14065