Set New EventManager in Context#CacheContext

[alexanderbez]

closes: #4868

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• Targeted PR against correct branch (see CONTRIBUTING.md)

• Linked to github-issue with discussion and accepted design OR link to spec that describes this work.

• Wrote tests

• Updated relevant documentation (docs/)

• Added a relevant changelog entry: clog add [section] [-t <tag>] [-m <msg>]

• Re-reviewed Files changed in the github PR explorer

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For Admin Use:

• Added appropriate labels to PR (ex. wip, ready-for-review, docs)
• Reviewers Assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #4873 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #4873      +/-   ##
==========================================
+ Coverage   54.29%   54.31%   +0.01%     
==========================================
  Files         271      271              
  Lines       17346    17346              
==========================================
+ Hits         9418     9421       +3     
+ Misses       7230     7227       -3     
  Partials      698      698