fix(k8s): make sure controllers start after leader election

[michaelbeaumont]

Summary

This PR adds an intercept to Manager.Add calls to save Controllers to be Added after leader election.

Closes #3611

[codecov-commenter]

Codecov Report

Merging #3666 (55f47b1) into master (999b7a8) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master    #3666   +/-   ##
=======================================
  Coverage   50.90%   50.91%           
=======================================
  Files         927      927           
  Lines       56508    56531   +23     
=======================================
+ Hits        28766    28781   +15     
- Misses      25453    25459    +6     
- Partials     2289     2291    +2     

Impacted Files	Coverage Δ
pkg/plugins/bootstrap/k8s/plugin.go	1.11% <0.00%> (-0.17%)	⬇️
pkg/defaults/components.go	86.95% <0.00%> (-4.35%)	⬇️
pkg/core/resources/model/rest/resource.go	67.94% <0.00%> (-1.29%)	⬇️
pkg/xds/generator/direct_access_proxy_generator.go	86.95% <0.00%> (+1.08%)	⬆️
pkg/insights/resyncer.go	73.61% <0.00%> (+2.45%)	⬆️
pkg/events/eventbus.go	92.59% <0.00%> (+7.40%)	⬆️
pkg/plugins/runtime/gateway/route/sorter.go	71.79% <0.00%> (+10.25%)	⬆️
pkg/insights/components.go	100.00% <0.00%> (+30.00%)	⬆️

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