Fixes #29591 - Replaced the double bracket testing to builtin test
Depending on the active shell, the efibootmgr_netboot snippet will throw an error in the finish.sh script like /tmp/finish.sh: 325: /tmp/finish.sh: [[: not found
Related issues
Bug #29591: Efibootmgr_netboot assumes bash is used.
Fixes #29591 - Replaced the double bracket testing to builtin test
Depending on the active shell, the efibootmgr_netboot snippet will throw
an error in the finish.sh script like
/tmp/finish.sh: 325: /tmp/finish.sh: [[: not found