[graph] fixes to the transformGraph logic

We need to recompute transformGraph, I try to do this intelligently
depending on params change only.

Also, I added preservation of louvain colouring.
2 jobs for 496-graph-explorer-regressions in 0 seconds (queued for 111 minutes and 7 seconds)
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Status Job ID Name Coverage
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failed #5943
deps

failed #5944
test

 
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