test(runtime): Add controllermanager tests

[irvinlim]

Adds unit tests for controllermanager.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@838149a). Click here to learn what that means.
The diff coverage is 50.00%.

@@           Coverage Diff           @@
##             main      #44   +/-   ##
=======================================
  Coverage        ?   54.47%           
=======================================
  Files           ?      163           
  Lines           ?     8095           
  Branches        ?        0           
=======================================
  Hits            ?     4410           
  Misses          ?     3477           
  Partials        ?      208           

Impacted Files	Coverage Δ
cmd/execution-controller/main.go	0.00% <0.00%> (ø)
pkg/runtime/controllermanager/controller.go	91.80% <100.00%> (ø)

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