Delete reactions added to issues and comments when deleting repository

[lafriks]

As title

[codecov-io]

Codecov Report

Merging #4232 into master will increase coverage by <.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #4232      +/-   ##
==========================================
+ Coverage   19.95%   19.96%   +<.01%     
==========================================
  Files         153      153              
  Lines       30518    30521       +3     
==========================================
+ Hits         6091     6094       +3     
- Misses      23512    23513       +1     
+ Partials      915      914       -1

Impacted Files	Coverage Δ
models/repo.go	17.82% <0%> (-0.04%)	⬇️
modules/process/manager.go	73.91% <0%> (+4.34%)	⬆️

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[lunny]

LGTM

[techknowlogick]

@lafriks does this need a backport?

[lafriks]

I can create one probably