fix: Configure paypal on charge request

[iamareebjamal]

Fixes #6872

The charge function was missing the paypal configure method call. And so, in case payment create and charge requests were handled by the same worker, then everything worked correctly since the configuration was done on the payment creation call, so the worker got configured for the charge request. But in case, charge request was handled by a new worker which did not create the payment, it would be uninitialized with the config, hence throw the error. This was fixed by using environment variables as they are global

[codecov]

Codecov Report

Merging #7305 into development will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@               Coverage Diff               @@
##           development    #7305      +/-   ##
===============================================
- Coverage        64.00%   63.99%   -0.01%     
===============================================
  Files              259      259              
  Lines            13075    13076       +1     
===============================================
  Hits              8368     8368              
- Misses            4707     4708       +1     

Impacted Files	Coverage Δ
app/api/helpers/payment.py	24.05% <0.00%> (-0.16%)	⬇️

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