db: improve performance of VersionManager.Copy by 40% just by providing size hint

[odeke-em]

Summary of Bug

If we examine the code in here

cosmos-sdk/db/version_manager.go

Lines 126 to 132 in c1b6ace

	func (vm *VersionManager) Copy() *VersionManager {
	vmap := make(map[uint64]struct{})
	for ver, _ := range vm.versions {
	vmap[ver] = struct{}{}
	}
	return &VersionManager{versions: vmap, initial: vm.initial, last: vm.last}
	}

we can see this interesting piece of code

cosmos-sdk/db/version_manager.go

Line 127 in c1b6ace

vmap := make(map[uint64]struct{})

That code should use a hint to make it even faster and here are some exhibits https://dashboard.bencher.orijtech.com/benchmark/213d0080ec47409d95c512bca4a8a27e with improvements in every dimension

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