tests/qemu-iotests/group: Re-use the "auto" group for tests that can always run

Currently, all tests are in the "auto" group. This is a little bit pointless.
OTOH, we need a group for the tests that we can automatically run during
"make check" each time, too. Tests in this new group are supposed to run
with every possible QEMU configuration, for example they must run with every
QEMU binary (also non-x86), without failing when an optional features is
missing (but reporting "skip" is ok), and be able to run on all kind of host
filesystems and users (i.e. also as "nobody" or "root").
So let's use the "auto" group for this class of tests now. The initial
list has been determined by running the iotests with non-x86 QEMU targets
and with our CI pipelines on Gitlab, Cirrus-CI and Travis (i.e. including
macOS and FreeBSD).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190502084506.8009-7-thuth@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>