refactor: Remove confusing OutputType::CHANGE_AUTO

Summary:

interfaces: Remove unused getDefaultChangeType

https://github.com/bitcoin/bitcoin/pull/19396/commits/fa2eb383522249a5f4d48726c520cec5de496614

Remove confusing OutputType::CHANGE_AUTO

https://github.com/bitcoin/bitcoin/pull/19396/commits/faddad71f648ed99734f4f8811bd4bc7232ca670

Enable Wswitch for OutputType

https://github.com/bitcoin/bitcoin/pull/19396/commits/fa927ff884ae373c676deed63180a8d238872cdc

This is a backport of core#19396

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D9974