fix: channel must exist before channel creator check

Description

Noticed a bit of bad DX when I was sending in the wrong channel-id to register counterparty. Since it was checking the creator first, I got creator not found, when the real issue was that the channel id was not correct (channel not found). Moved the check up and adjusted the test to catch this.

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cosmos / ibc-go

fix: channel must exist before channel creator check #7538

Description

Quality Gate passed for 'ibc-go'