refactor: remove proctored exams card and FEATURE_TURN_PAYMENT_OFF flag

[arslanashraf7]

Pre-Flight checklist

• [x] Screenshots and design review for any changes that affect layout or styling
  • [x] Desktop screenshots
  • [ ] Mobile width screenshots
• [x] Testing
  • [ ] Code is tested
  • [x] Changes have been manually tested

What are the relevant tickets?

5282

What's this PR do?

• Refactored the code to remove FEATURE_TURN_PAYMENT_OFF
• Removed any conditions and the Proctored exam card from the dashboard

How should this be manually tested?

• Setup on this branch
• Load the dashboard and you should not see a Proctored Exam card on the dashboard
• Try to set FEATURE_TURN_PAYMENT_OFF to False and see that there should still be no proctored exam card
• As a matter of fact, adding FEATURE_TURN_PAYMENT_OFF in .env should not affect anything at all now
• Nothing should break

Where should the reviewer start?

Might be a good place to start testing by first enabling the Proctored Exam card as mentioned in the ticket by enabling FEATURE_TURN_PAYMENT_OFF so that it's visible on the dashboard, then shift to this branch

Any background context you want to provide?

We introduced this flag recently when we turned off the payments for MM, It was done in https://github.com/mitodl/micromasters/pull/5230/files

Screenshots (if appropriate)

After refactoring and removal of FEATURE_TURN_PAYMENT_OFF flag

[arslanashraf7]

did you also remove "/components/dashboard/FinalExamCard.js"? It is not in this PR.

No, I didn't remove it. Thought we'd do it in a cleanup PR. But I'll remove it since it might not need a lot of refactoring.

[codecov-commenter]

Codecov Report

Merging #5289 (a6f1f58) into master (9b536aa) will decrease coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5289      +/-   ##
==========================================
- Coverage   93.65%   93.64%   -0.01%     
==========================================
  Files         501      499       -2     
  Lines       23125    23089      -36     
  Branches      967      967              
==========================================
- Hits        21657    21621      -36     
  Misses       1361     1361              
  Partials      107      107              

Impacted Files	Coverage Δ
ui/views.py	92.30% <ø> (ø)
static/js/containers/DashboardPage.js	85.37% <100.00%> (-0.13%)	:arrow_down:

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[arslanashraf7]

@annagav I've removed it in https://github.com/mitodl/micromasters/pull/5289/commits/a6f1f58774593d383e8ed361d45ea657fc695eaa.

[arslanashraf7]

@pdpinch should I go ahead and merge this or do you have any reservations? Asking this because you had a comment on that actual ticket https://github.com/mitodl/micromasters/issues/5282#issuecomment-1397032516.