NAS-128390 / 25.04 / Adjust min child count when creating draid pools

[RehanY147]

Changes:

Adjusts min allowed child count when creating dRaid pools

Testing:

The children select's minimum value when creating a draid pool should be calculated based on this formula

max = Math.min(maxAvailableDisks, 255)
parity = 1 if dRaid1, 2 if dRaid2, 3 if dRaid3
min = (data vdev disks) + (hot spares count) + parity

[bugclerk]

Jira URL: https://ixsystems.atlassian.net/browse/NAS-128390

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.29%. Comparing base (8c8c3c6) to head (5b9f8f2).
Report is 4 commits behind head on master.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #11115   +/-   ##
=======================================
  Coverage   82.28%   82.29%           
=======================================
  Files        1650     1650           
  Lines       57730    57729    -1     
  Branches     5948     5948           
=======================================
+ Hits        47506    47508    +2     
+ Misses      10224    10221    -3     

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[undsoft]

I was able to create a pool with more children now.

[bugclerk]

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