fix NFT sims preformance

[fedekunze]

Summary of Bug

Adding the x/nft simulation messages makes the Simapp tests very slow (46m) which is >2x than the avg sim time. This was experienced during the last commits of cosmos/cosmos-sdk#4838. The solution was to remove the nft simulations from the simapp until we solve this issue. This could probably related to either #6 or the custom (Un)MarshalJSON used by the nft module used to return an Object-like response instead of an Array.

The most affected simulation seems to be test_sim_nondeterminism, the other sim tests finish earlier but wait for it to finish. Weirdly enough, test_sim_nondeterminism doesn't run any invariants that could explain the bad performance.

I reduced the NFT operations weight and the number of accounts that hold NFTs (from 50% to 15%) but didn't improve the performance much.

Version

a90002f

Steps to Reproduce

• Add the nft module to the sim manager
• Add nft operations

(see 68a1a9c)

cc: @rigelrozanski @alexanderbez @okwme

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[tac0turtle]

@fedekunze is this still relevant with nft moving to the modules repo?

[fedekunze]

yes it's still relevant as the simulations don't perform well with the current state of the NFT module. Moving this to the https://github.com/cosmos/modules repo