refactor: Remove RandomizedParams from AppModuleSimulation interface

[poorphd]

Description

RandomizedParams has been removed from the AppModuleSimulation interface. Previously, it generated random parameter changes during simulations through ParamChangeProposal, which is now legacy. Since all modules have been migrated away from using ParamChangeProposal, we can now safely remove RandomizedParams from the interface.

Adding simulation (including MsgUpdateParams proposal) will be added in a separated PR,

Closes: L-2, L-7

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[poorphd]

simulation for other canto modules are in a separated PR #65

[dudong2]

IMO it looks good to merge this PR with pr-65, as modifications to the x/coinswap are also being made on pr-65, which causes confusion.