nixos/tests/installer: Fix matching LUKS prompt
nixos/tests/installer: Fix matching LUKS prompt

The LUKS passphrase prompt has changed from "Enter passphrase" to "Enter
LUKS Passphrase" in c69c76ca7efecba24aba555c2a03f933997d1fd5, so the OCR
detection of the test fails indefinitely.

Unfortunately, this doesn't fix the test because we have a real problem
here:

Enter LUKS Passphrase:
killall: cryptsetup: no process killed
Enter LUKS Passphrase:

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@redmoonstudios.org>
Cc: da39a3ee5e6b4b0d3255bfef95601890afd80709@abbradar

SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs