fix(tests): fix simulation test invalid genesis state

[RiccardoM]

Description

This PR fixes the simulation tests by removing invalid x/rewards genesis accumulated commissions initialization.

The previous code created random accumulated commissions for random targets. However, this caused the following error when running some simulations:

Simulating... block 2/100, operation 100/237. Logs to writing to $HOME/.simapp/simulations/1734395338592.log
    simulate.go:345: error on block  2/100, operation (138/237) from x/operators:
        recovered: negative coin amount

This error was raised while trying to execute a MsgDeleteOperator on an operator that had some accumulated commissions, but whose outstanding rewards were empty. When running the clean up code, the error would be raised since the outstanding would be zero:

// Subtract from outstanding
outstanding = outstanding.Sub(commission)

This could be verified running the determinism tests with seed 2282874401958575228:

go test -mod=readonly ./app -run TestAppStateDeterminism -Enabled=true \
	-Seed 2282874401958575228 -NumBlocks=100 -BlockSize=200 \
	-Commit=true -Period=0 -v -timeout 24h

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[github-actions]

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Build	Format	Lint	Breaking	Updated (UTC)
✅ passed	✅ passed	✅ passed	✅ passed	Dec 17, 2024, 1:08 AM

[hallazzang]

LGTM