Eliminate need to x/swingset params migration in upgrade handler

[JimLarson]

What is the Problem Being Solved?

Upgrade-13 introduced (#8623) a new block into the upgrade handler:

m := swingsetkeeper.NewMigrator(app.SwingSetKeeper)
		err = m.MigrateParams(ctx)
		if err != nil {
			return mvm, err
		}

and this was propagated in the upgrade-14 and -15 handlers.

We don't want permanent entries like this in the upgrade handler. The minimal upgrade handler should simply call the per-module migrations:

		// Always run module migrations
		mvm, err := app.mm.RunMigrations(ctx, app.configurator, fromVm)
		if err != nil {
			return mvm, err
		}

Description of the Design

Ideally do any parameter migration as a per-module migration as needed.

Security Considerations

Scaling Considerations

Test Plan

Upgrade Considerations