Shouldn't check wallet before requests that doesn't require wallet.

[devyetii]

Most of GET requests in zcncore like this one: https://github.com/0chain/gosdk/blob/f0d08895c0f1a0abd22f884a8d2fa767c2acbf25/zcncore/wallet_base.go#L1006-L1017

checks for valid wallet, however the wallet is not needed for such a request, should only check sdk config. This affect 0box, for example, since no wallet is configured for it usually.

Related discussion: https://0chain.slack.com/archives/C04EFTQH26T/p1682726300357019