tests: Make ovsdb test more robust and faster.

Using sleep's is prone to runtime system dependent races, and indeed
this test started consistently failing on my dev VM after an unrelated
change to ovs-vswitchd.  Get git of the sleeps and explicitly wait for
the transaction on ovsdb1 to become visible on ovsdb2.

Also fix the name of the test.

Signed-off-by: Jarno Rajahalme <jarno@ovn.org>
Signed-off-by: Ben Pfaff <blp@ovn.org>
Acked-by: Andy Zhou <azhou@ovn.org>
Tested-by: Joe Stringer <joe@ovn.org>