fix: accept all 200 responses as OK in courier

[aeneasr]

Closes #3399

Related issue(s)

Checklist

• I have read the contributing guidelines.
• I have referenced an issue containing the design document if my change
  introduces a new feature.
• I am following the
  contributing code guidelines.
• I have read the security policy.
• I confirm that this pull request does not address a security
  vulnerability. If this pull request addresses a security vulnerability, I
  confirm that I got the approval (please contact
  [email protected]) from the maintainers to push
  the changes.
• I have added tests that prove my fix is effective or that my feature
  works.
• I have added or changed the documentation.

Further Comments

[codecov]

Codecov Report

Merging #3401 (7bb0eb8) into master (013f335) will increase coverage by 0.00%.
Report is 2 commits behind head on master.
The diff coverage is 30.00%.

❗ Current head 7bb0eb8 differs from pull request most recent head 8af97e6. Consider uploading reports for the commit 8af97e6 to get more accurate results

@@           Coverage Diff           @@
##           master    #3401   +/-   ##
=======================================
  Coverage   78.03%   78.03%           
=======================================
  Files         327      327           
  Lines       21373    21370    -3     
=======================================
- Hits        16678    16677    -1     
+ Misses       3458     3456    -2     
  Partials     1237     1237           

Files Changed	Coverage Δ
courier/http.go	55.55% <30.00%> (+1.38%)	⬆️

... and 3 files with indirect coverage changes

[hperl]

LGTM!