Fix local devcontainers

[a-b]

Over the last year, the devcontainer setup drifted and stopped working on the local macOS. This PR addresses it.

• [x] I have reviewed the contributing guide

• [x] I have viewed, signed, and submitted the Contributor License Agreement

• [x] I have made this pull request to the main branch

• [x] I have run all the unit tests using bundle exec rake

• [ ] I have run CF Acceptance Tests

[johha]

@a-b What issues in particular did you encounter? We're using the dev setup regularly and don't have any issue (at least with RubyMine/IntelliJ).