AccountMapper.IterateAccounts may leak resource

[goolAdapter]

Summary of Bug

AccountMapper.IterateAccounts may leak resource.

Steps to Reproduce

cosmos-sdk/x/auth/mapper.go

Line 89 in d5652d9

iter := sdk.KVStorePrefixIterator(store, []byte("account:"))

Iterator need to Close after use，this may leak a go routine for iavlIterator.

almost all of Iterator implement is trival，but iavlIterator.Close is no-trival.
see

cosmos-sdk/store/iavlstore.go

Line 372 in d5652d9

close(iter.quitCh)

in democoin/oracle/handle.go also has a similar case，but it's a full iterator，here only cause confusion，not incorrect.

cosmos-sdk/examples/democoin/x/oracle/handler.go

Line 30 in bce0905

iter := sdk.KVStorePrefixIterator(store, prefix)

This Issue is base on tag v0.24.0

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[ValarDragon]

Your totally right! Thanks for catching this. Would you like to submit a PR to fix this?