Do not use a custom http.Transport due to Resty incompatibility

[okokes-akamai]

We're hitting the same issue as here: linode/cluster-api-provider-linode#436

When we use a custom CA, it doesn't get used.

Given that we construct an http.Transport that is of a different concrete type than http.Transport (it just needs to be a RoundTripper), resty fails and defaults to an empty client, discarding our CA.

General:

• Have you removed all sensitive information, including but not limited to access keys and passwords?
• Have you checked to ensure there aren't other open or closed Pull Requests for the same bug/feature/question?

Pull Request Guidelines:

1. Does your submission pass tests?
2. Have you added tests?
3. Are you addressing a single feature in this PR?
4. Are your commits atomic, addressing one change per commit?
5. Are you following the conventions of the language?
6. Have you saved your large formatting changes for a different PR, so we can focus on your work?
7. Have you explained your rationale for why this feature is needed?
8. Have you linked your PR to an open issue

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 55.52%. Comparing base (f2b7e2a) to head (1fccf33).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #227      +/-   ##
==========================================
- Coverage   55.64%   55.52%   -0.12%     
==========================================
  Files          12       12              
  Lines        1887     1882       -5     
==========================================
- Hits         1050     1045       -5     
  Misses        694      694              
  Partials      143      143              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[rahulait]

LGTM