bug#41709: installed-os test failing

[Mathieu Othacehe]

Hello

The installed-os test is failing because the image closure is (again)
bigger than the allocated 1.4GiB in the test partition.

--8<---------------cut here---------------start------------->8---
guix size $(./pre-inst-env guix system build 
gnu/system/examples/bare-bones.tmpl)
--8<---------------cut here---------------end--------------->8---

reports 1397.3 MiB.

By reverting this commit 0eed77127592323d89f56c215a15374a1aaae110
(introducing an extra glibc to %default-locale-libcs), it drops down to:

1305.5 MiB.

Now multiple options:

* Revert this commit.
* Find other system closure improvements.
* Up the limit to 1.5GiB.

WDYT?

Thanks,

Mathieu