Make the jest-circus export compatible with regular runners

[captbaritone]

This will make it easier to use jest-circus using the regular runner config.

@aaronabramov

[codecov-io]

Codecov Report

Merging #6312 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #6312      +/-   ##
==========================================
- Coverage   63.67%   63.65%   -0.03%     
==========================================
  Files         226      227       +1     
  Lines        8634     8637       +3     
  Branches        3        4       +1     
==========================================
  Hits         5498     5498              
- Misses       3135     3138       +3     
  Partials        1        1

Impacted Files	Coverage Δ
packages/jest-runner/src/run_test.js	5.08% <ø> (ø)	⬆️
...ircus/src/legacy_code_todo_rewrite/jest_adapter.js	0% <0%> (ø)	⬆️
packages/jest-circus/runner.js	0% <0%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 3a3b4e3...ddc8f9e. Read the comment docs.

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
Please note this issue tracker is not a help forum. We recommend using StackOverflow or our discord channel for questions.