tests/avocado: Remove non-working sparc leon3 test

tests/avocado: Remove non-working sparc leon3 test

The test has been marked as broken more than 4 years ago, and
so far nobody ever cared to fix it. Thus let's simply remove it
now ... if somebody ever needs it again, they can restore the
file from an older version of QEMU.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Clément Chigot <chigot@adacore.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240710111755.60584-1-thuth@redhat.com>
[AJB: fix MAINTAINERS]
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240718094523.1198645-3-alex.bennee@linaro.org>