kyua: convert some tests for execenv=jail demo

[igoro]

Summary

This is a supplementary patch for https://reviews.freebsd.org/D42350.

Test Plan

In order to test Kyua jail support against main:

• apply kyua patch: https://reviews.freebsd.org/D42350
• apply jailed tests demo patch: https://reviews.freebsd.org/D44087
• full build
• kldload pf if_epair
• (jailed parallelism test only) kyua -v parallelism=$(sysctl -n hw.ncpu) test -k /usr/tests/sys/netpfil/pf/Kyuafile pass_block
  • optionally it can be run without parallelism to compare timings
• (full suite test) kyua test -k /usr/tests/Kyuafile

Extra testing for the cases without jail feature:

• apply kyua patch: https://reviews.freebsd.org/D42350
• apply jailed tests demo patch: https://reviews.freebsd.org/D44087
• full build WITHOUT_JAIL
• (jailed parallelism test only) kyua -v parallelism=$(sysctl -n hw.ncpu) test -k /usr/tests/sys/netpfil/pf/Kyuafile pass_block
  • it should report what those tests are skipped due to execenv=jail is not supported
• (full suite test) kyua test -k /usr/tests/Kyuafile

[igoro]

This is not required anymore and the actual examples can be found within main, e.g. https://cgit.freebsd.org/src/commit/?id=4f752a1583dc97d166caae7f844bf42715e99978.