Require aws-sdk-go-v2 instead of aws-sdk-go

Require the github.com/aws/aws-sdk-go-v2 modules the migrated source imports — the core, config, credentials, the relocated feature packages and each service — along with the indirect requirements they bring, and add their go.sum lines, so the module builds without a go mod tidy. Drop github.com/aws/aws-sdk-go once no file imports it. A module the build list already selects at a higher version keeps it. Then run go mod tidy: the build does not need it, but it drops what the migration leaves behind — the requirements only v1 needed, the go.sum lines nothing reads any more, and an // indirect marker on a module the source now imports directly.