ovsdb-server.at: Skip tests that use ovsdb-server's "--run" on Windows.

ovsdb-server's port on Windows does not support the "--run" option.
The two tests skipped in this commit make use of "--run" option to
test ovsdb-server's truncating of corrupt log or bad transaction.
It looks a little tricky to get this test running on Windows without
the "--run" option implemented.

Signed-off-by: Gurucharan Shetty <gshetty@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>