tests/avocado: Remove the remainders of the virtiofs_submounts test

The virtiofs_submounts test has been removed in commit 5da7701e2a
("virtiofsd: Remove test"), so we don't need this files anymore.

Message-ID: <20240718173125.489901-1-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
4 files changed