remove custom migration + delete from all lists

[danlipert]

Description

This change removes the custom migration for funder/hunter personas, instead relying on the cronjob to set the flags for each user. The management command can be run manually on production after deploy.

The second commit also deletes users from the additional mailchimp lists if they delete their account.

Refers/Fixes

Fixes migration errors, delete from funder and hunter lists

Testing

Tested via successful test suite run

[codecov]

Codecov Report

Merging #4702 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #4702   +/-   ##
=======================================
  Coverage   30.43%   30.43%           
=======================================
  Files         216      216           
  Lines       17192    17192           
  Branches     2324     2324           
=======================================
  Hits         5232     5232           
  Misses      11753    11753           
  Partials      207      207

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[codecov]

Codecov Report

Merging #4702 into master will decrease coverage by 0.01%.
The diff coverage is 12%.

@@            Coverage Diff             @@
##           master    #4702      +/-   ##
==========================================
- Coverage   30.43%   30.42%   -0.02%     
==========================================
  Files         216      216              
  Lines       17192    17201       +9     
  Branches     2324     2325       +1     
==========================================
+ Hits         5232     5233       +1     
- Misses      11753    11761       +8     
  Partials      207      207

Impacted Files	Coverage Δ
app/marketing/views.py	12.15% <33.33%> (+0.15%)	⬆️
app/marketing/utils.py	32.65% <9.09%> (-4.15%)	⬇️

---

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