[al] Fixed dead loop issue when deleting node

[csyshing]

When our Python translator runs, somehow deleting leaf transform node is making parent transform nodes being deleted, e.g. if deleting /root/char/bindings, /root/char and /root Maya nodes would be invalid, this is causing dead loop problem when traversing the transform chain in AL_USDMaya.

AL_USDMaya used to use the trick below to delete Maya nodes without affecting parent transform nodes:

modifier.reparentNode(object);
modifier.deleteNode(object);

but for some reason it's not working, this PR is changing to use MGlobal::deleteNode() method instead.

[csyshing]

Hi @ppt-adsk , the Jenkins log says these tests are failing:

    The following tests FAILED:
    	 83 - testVP2RenderDelegateDisplayColors (Failed)
    	 84 - testVP2RenderDelegateGeomSubset (Failed)
    	 85 - testVP2RenderDelegatePointInstanceOrientation (Failed)
    	 86 - testVP2RenderDelegateTextureLoading (Failed)
    	 87 - testVP2RenderDelegateDuplicateProxy (Failed)
    	 88 - testVP2RenderDelegateInteractiveWorkflows (Failed)
    	 89 - testVP2RenderDelegatePointInstanceSelection (Failed)
    	 90 - testVP2RenderDelegatePointInstancesPickMode (Failed)
    	 91 - testVP2RenderDelegatePrimPath (Failed)
    	 92 - testVP2RenderDelegateUSDPreviewSurface (Failed)
    	 93 - testVP2RenderDelegateConsolidation (Failed)
    	 94 - testVP2RenderDelegatePerInstanceInheritedData (Failed)
    	 95 - testVP2RenderDelegateBasisCurves (Failed)
    	 96 - testVP2RenderDelegateDrawModes (Failed)
    	 97 - testVP2RenderDelegateUsdCamera (Failed)
    	 98 - testVP2RenderDelegateSelection (Failed)
    	 99 - testVP2RenderDelegateUsdSkel (Failed)
    	100 - testVP2RenderDelegateMaterialX (Failed)
    	101 - testVP2RenderDelegateIsolateSelect (Failed)
    	102 - testMtohBasicRender (Failed)
    	104 - testMtohDagChanges (Failed)
    	105 - testMtohVisibility (Failed)

I cannot reproduce those errors locally, I can see other PRs are also failing in similar tests as well.
I am not sure what was wrong but let me know if I need to update anything for my PR, cheers!

[csyshing]

Merged latest dev as well, hopefully the unit tests can pass fine.

[ppt-adsk]

Only Linux interactive graphics tests failing, unrelated fix for this problem up-coming, so ready for merge.