ci/lava: Feed yaml.load with raw bytes data

ci/lava: Feed yaml.load with raw bytes data

LAVA uses XMLRPC to send jobs information and control, more specifically
it sends device logs via YAML dumps encoded in UTF-8 bytes.

In Python, we have xmlrpc.client.Binary class as the serializer
protocol, we get the logs wrapped by this class, which encodes the data
as UTF-8 bytes data.

We were converting the encoded data to a string via the `str` function,
but this led the loaded YAML data to use single quotes instead of double
quotes for string values that made special characters, such as `\x1b` to
be escaped as `\\x1b`.

With this fix, we can now drop one of the hacks that fixed the bash
colors.

Signed-off-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20051>