ci: Enable testing GLES2-3 on a530 (Dragonboard 820c).

Following on from the db410c conversion to baremetal testing, reuse the
same scripts in the same rack to run 7 db820c boards (#4/8 is failing in
the bootloader for unknown reasons).

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4177>
7 files changed