selftests/tc-testing: Add selftests for qdisc DualPI2

Update configuration of tc-tests and preload DualPI2 module for self-tests,
and add following self-test cases for DualPI2:

  Test a4c7: Create DualPI2 with default setting
  Test 1ea4: Create DualPI2 with memlimit
  Test 2130: Create DualPI2 with typical_rtt and max_rtt
  Test 90c1: Create DualPI2 with max_rtt
  Test 7b3c: Create DualPI2 with any_ect option
  Test 49a3: Create DualPI2 with overflow option
  Test d0a1: Create DualPI2 with drop_enqueue option
  Test f051: Create DualPI2 with no_split_gso option
  Test 456b: Create DualPI2 with packet step_thresh
  Test 610c: Create DualPI2 with packet min_qlen_step
  Test b4fa: Create DualPI2 with packet coupling_factor
  Test 37f1: Create DualPI2 with packet classic_protection

Signed-off-by: Chia-Yu Chang <chia-yu.chang@nokia-bell-labs.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Link: https://patch.msgid.link/20250722095915.24485-6-chia-yu.chang@nokia-bell-labs.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>