bug#41668: Failing test: gui-installed-desktop-os-encrypted

[Brice Waegeneire]

Hello Guix,

For some time now the system test 'gui-installed-desktop-os-encrypted'
doesn't succeed, the last time it passed was 2020-04-11[0]. This is
problematic since it exercise a lot of packages and thus can be used to
test those packages. Ludovic attempted to fixed it[1] but it didn't 
fixed
the test on my side.

[0]: 
http://ci.guix.gnu.org/search?query=gui-installed-desktop-os-encrypted+system%3Ax86_64-linux+spec%3Aguix-master+status%3Asuccess
[1]: https://issues.guix.info/40790#7

- Brice