[COST-5796] correctly log exception outside log_json function

[djnakabaale]

Jira Ticket

COST-5796

Description

This change is a followup on #5431, to correctly pass exception outside log_json function.

Testing

1. Checkout Branch
2. Restart Koku
3. Run unit test and see log message

python3 koku/manage.py test koku.test_middleware.IdentityHeaderMiddlewareTest.test_create_customer_integrity_error_existing_customer

Release Notes

• correctly log exception outside log_json function

* [COST-5796](https://issues.redhat.com/browse/COST-5796) correctly log exception outside log_json function

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.2%. Comparing base (aabdbae) to head (80e699d).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5448   +/-   ##
=====================================
  Coverage   94.2%   94.2%           
=====================================
  Files        370     370           
  Lines      31539   31539           
  Branches    3378    3378           
=====================================
+ Hits       29700   29702    +2     
+ Misses      1196    1195    -1     
+ Partials     643     642    -1