[scripts] Hide password

Summary:
issue: ENG-6874
We want to hide the password in console

Test Plan:
ran $PRJ_ROOT/scripts/set-up-authoritative-keyserver.sh from dev-shell.nix
checked that the password is not visible

Reviewers: tomek, michal

Reviewed By: tomek

Subscribers: ashoat

Differential Revision: https://phab.comm.dev/D11258