chore: remove cosmossdk.io/api module from v0.46.x

[aleem1314]

Description

v0.46 is not using cosmossdk.io/api. Left over from #12353.

We are facing the following issue while updating to SDK v0.46.

panic: proto: file "cosmos/base/query/v1beta1/pagination.proto" is already registered
        previously from: "cosmossdk.io/api/cosmos/base/query/v1beta1"
        currently from:  "github.com/cosmos/cosmos-sdk/api/cosmos/base/query/v1beta1"
See https://developers.google.com/protocol-buffers/docs/reference/go/faq#namespace-conflict

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[amaury1093]

makes sense, thanks @aleem1314 !

[alexanderbez]

What's up with TestIntegrationTestSuite/TestGetTxEvents_GRPCGateway failing?