Revert "(#16157) ensure that mirror and raidz are used as subcommands"

This reverts commit ccc3a566fdde5426822489ffaeb25dc8abf26967.
(PUP-3388) Add tests for creating mirror and raidz virtual devices

Adds tests to ensure we can create mirror and raidz virtual devices.
Merge pull request #3299 from joshcooper/ticket/master/PUP-3388-revert-zpool-raidz-mirror

(PUP-3388) Fix regression when creating zpool raidz and mirror virtual devices