Ensure cluster detail machine and node lists are grouped correctly

[richard-cox]

Summary

Fixes #13285

Occurred changes and/or fixed issues

• the ResourceTable's used for rke1 nodes and rke2 machines incorrectly disabled grouping
• grouping however was broken under the hood and showed them anyway
• this was fixed in fixed in Add server-side pagination to home page cluster list #11663
  • specifically the addition of the if in

     computedGroupBy() {
       // If we're not showing grouping options we shouldn't have a group by property
       if (!this.showGrouping) { return null; } 
  

• the fix here is to remove the groupable=false to ensure grouping can show

I've validated that the issue does not occur in 2.10-head

Areas or cases that should be tested

• RKE1 and RKE2 clusters should show the pool and deployment groups when viewing the cluster detail pool tab list
• The groups, if the user has permission, should contain scaling controls

Screenshot/Video

Checklist

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