The fu_context_load_quirks(FU_QUIRKS_LOAD_FLAG_NO_CACHE) has to be done first,
otherwise fu_context_load_hwinfo() auto-loads the quirk db with the defaults.
Fixes a build failure in Fedora QA.
Explicitly load_hwinfo at start of mtd self test
```
.# Start of mtd tests
.# GLib-GIO-DEBUG: _g_io_module_get_default: Found default implementation local (GLocalVfs) for ?gio-vfs?
.# XbSilo-DEBUG: attempting to load /tmp/.E94WW1
.# XbSilo-DEBUG: failed to load silo: blob too small
Bail out! FuContext-FATAL-CRITICAL: cannot use HWIDs before calling ->load_hwinfo()
(/usr/libexec/installed-tests/fwupd/mtd-self-test:1758): FuContext-CRITICAL **: 23:27:43.095: cannot use HWIDs before calling ->load_hwinfo()
```
the autopkgtest environment in Ubuntu seems to not be preparing the mtdram
device properly. Sometimes the udev node "exists" but the /dev/mtd0 does not
exist.
Look for this explicitly and skip the test if it happens.
