launcher: Don't bail out on bash errors (#1769)
launcher: Don't bail out on bash errors (#1769)

To determine whether unprivileged user namespaces are enabled in the
user's kernel or not, we check the content of a file that will
probably be missing in most kernels where unprivileged user namespaces
have not been disabled by default.
This will trigger an error that we send to `/dev/null` but the `-e`
option of the launcher script forces the script to stop anyway.

Now that the script has been implemented and tested, we can remove
this option as well as the `-x` option which prints out every single
command.
cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop