mirror: if mirror test fails, suggest an offline install
In the mirror screen, if the test fails and the user decides to ignore
the failure, we used to continue the installation normally ; which in
most scenarios resulted in an error at a later stage of the
installation.
Instead, we now revert to an installation without network (i.e., only
packages from the pool are considered for installation) if the user
decides to ignore the failure.
storage: log snapd response text when v2/systems/{system} fails
When the request to v2/systems/enhanced-secureboot-desktop (or
equivalent) fails, Subiquity did not capture the reason. This makes
it difficult to understand why this call sometimes fails. We now log the
response text to understand better what's going on.
Grub provides "quiet splash" for GRUB_CMDLINE_LINUX_DEFAULT out of the
box, but curtin rewrites that value and drops both "quiet" and "splash".
On desktop, retain "quiet splash".
This should be configurable via autoinstall if this change is undesired.
