selftest: tcp: Add more bind() calls.

In addtition to the two addresses defined in the fixtures, this patch
add 6 more bind calls():

  * 0.0.0.0
  * 127.0.0.1
  * ::
  * ::1
  * ::ffff:0.0.0.0
  * ::ffff:127.0.0.1

The first two per-fixture bind() calls control how inet_bind2_bucket
is created, and the rest 6 bind() calls cover as many conflicting
patterns as possible.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240326204251.51301-7-kuniyu@amazon.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>