This is related to #30876. The AbstractSimpleTransportTestCase initiates
many tcp connections. There are normally over 1,000 connections in
TIME_WAIT at the end of the test. This is because every test opens at
least two different transports that connect to each other with 13
channel connection profiles. This commit modifies the default
connection profile used by this test to 6. One connection for each
type, except for REG which gets 2 connections.
cf9aff954e