test: improve PushController tests

[cbaker6]

New Pull Request Checklist

• I am not disclosing a vulnerability.
• I am creating this PR in reference to an issue.

Issue Description

Every once in awhile some of these tests fail on Postgres. The timer is set low, so giving it a small bump.

Related issue: #7180

Approach

Improve some of the PushController tests to use async/await. Increase sleep timer to prevent random failures on Postgres.

TODOs before merging

• Add tests
• A changelog entry is created automatically using the pull request title (do not manually add a changelog entry)

[parse-github-assistant]

Thanks for opening this pull request!

• 🎉 We are excited about your hands-on contribution!

[codecov]

Codecov Report

Merging #7760 (3e7c50a) into alpha (caf4a23) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##            alpha    #7760      +/-   ##
==========================================
+ Coverage   93.95%   93.96%   +0.01%     
==========================================
  Files         183      183              
  Lines       13640    13640              
==========================================
+ Hits        12815    12817       +2     
+ Misses        825      823       -2     

Impacted Files	Coverage Δ
src/RestWrite.js	94.20% <0.00%> (+0.15%)	⬆️
src/Adapters/Files/GridFSBucketAdapter.js	80.32% <0.00%> (+0.81%)	⬆️

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[cbaker6]

@mtrezza this is ready for review

[mtrezza]

Looks good, I see all beautiful green!

[parseplatformorg]

🎉 This change has been released in version 5.0.0-alpha.16

[parseplatformorg]

🎉 This change has been released in version 5.0.0-beta.10

[parseplatformorg]

🎉 This change has been released in version 5.1.0