Resolve "`Faraday::Connection#authorization` is deprecated"

What does this MR do and why?

This MR removes the dependency of using asana gem, and gets rid of Faraday::Connection#authorization is deprecated message. Logs are here. It relies on regular Gitlab::HTTP calls instead.

Screenshots or screen recordings

N/A

How to set up and validate locally

1. Checkout the branch
2. Visit the Settings/Integrations page
3. Active the Asana integration, and verify it works as expected 🎉

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #403192 (closed)