Simulation test: `out of gas` error when handling lot of denoms

[lumtis]

out of gas error may occur during simulation tests when having a lot of denoms handled, vouchers in our case Fees in simulation tests in SDK are paid with all denoms. Then all the denom rewards are auto-claimed which triggers the out of gas.

Potential solution on SDK:

• make auto-claim gasless
• change RandomFees to use a single denom

Potential solution on our chain:

• Limit number of created vouchers

Don't hesitate to put more information @giunatale

[giunatale]

For context, see also #369

[lumtis]

NOTE: when we want to perform big simulation, we can still decrease the weight for the operations minting vouchers and unredeeming

	defaultWeightMsgMintVouchers      = 1
	defaultWeightMsgUnredeemVouchers  = 1