Merge branch 'selftests-tc-increase-timeout-and-add-missing-kconfig'

Matthieu Baerts says:

====================
selftests: tc: increase timeout and add missing kconfig

When looking for something else in LKFT reports [1], I noticed that the
TC selftest ended with a timeout error:

  not ok 1 selftests: tc-testing: tdc.sh # TIMEOUT 45 seconds

I also noticed most of the tests were skipped because the "teardown
stage" did not complete successfully. It was due to missing kconfig.

These patches fix these two errors plus an extra one because this
selftest reads info from "/proc/net/nf_conntrack". Thank you Pedro for
having helped me fixing these issues [2].

Link: https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230711/testrun/18267241/suite/kselftest-tc-testing/test/tc-testing_tdc_sh/log [1]
Link: https://lore.kernel.org/netdev/0e061d4a-9a23-9f58-3b35-d8919de332d7@tessares.net/T/ [2]
====================

Link: https://lore.kernel.org/r/20230713-tc-selftests-lkft-v1-0-1eb4fd3a96e7@tessares.net


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