tests/functional: convert tests to new uncompress helper

Replace use of lzma_uncompress and gzip_uncompress with the
new uncompress helper.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20241217155953.3950506-27-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
14 files changed