chore: fix x/mint param sims (cosmos#12461)

`RandomizedParams` generates random parameter changes during simulations, however, it does so through `ParamChangeProposal` which is now legacy. 

Once all modules are migrated we will remove `RandomizedParams` entirely from the simulation interface.

For now, we just return an empty slice.

.github/workflows/test.yml

@@ -291,7 +291,6 @@ jobs:
             **/**.go
             go.mod
             go.sum
-        if: env.GIT_DIFF
       - name: test-sim-nondeterminism
         run: |
           make test-sim-nondeterminism

x/mint/module.go

@@ -207,8 +207,12 @@ func (AppModule) ProposalContents(simState module.SimulationState) []simtypes.We
 }
 
 // RandomizedParams creates randomized mint param changes for the simulator.
+//
+// TODO: Returns an empty slice which will make parameter changes a no-op during
+// simulations. Once all modules are migrated, remove RandomizedParams from
+// the simulation interface.
 func (AppModule) RandomizedParams(r *rand.Rand) []simtypes.ParamChange {
-	return simulation.ParamChanges(r)
+	return []simtypes.ParamChange{}
 }
 
 // RegisterStoreDecoder registers a decoder for mint module's types.