Retire legacy test infrastructure

• Removed zpios kmod, utility, headers and man page.

• Removed unused scripts zpios-profile/*, zpios-test/*, zpool-config/*, smb.sh, zpios-sanity.sh, zpios-survey.sh, zpios.sh, and zpool-create.sh.

• Removed zfs-script-config.sh.in. When building 'make' generates a common.sh with in-tree path information from the common.sh.in template. This file and sourced by the test scripts and used for in-tree testing, it is not included in the packages. When building packages 'make install' uses the same template to create a new common.sh which is appropriate for the packaging.

• Removed unused functions/variables from scripts/common.sh.in. Only minimal path information and configuration environment variables remain.

• Removed unused scripts from scripts/ directory.

• Remaining shell scripts in the scripts directory updated to cleanly pass shellcheck and added to checked scripts.

• Renamed tests/test-runner/cmd/ to tests/test-runner/bin/ to match install location name.

• Removed last traces of the --enable-debug-dmu-tx configure options which was retired some time ago.

Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6509