[RHCLOUD-36497] - switch error messages from sources to integrations

[lcouzens]

Jira Ticket

RHCLOUD-36497

Description

The UI team has spotted an error message that makes a reference to "sources" instead of integrations, which would confuse users and customers.

Testing

1. Checkout Branch
2. Restart Koku
3. Hit endpoint or launch shell
   1. You should see ...
4. Do more things...

Release Notes

• proposed release note

* [RHCLOUD-36497](https://issues.redhat.com/browse/RHCLOUD-36497) Replace "sources" references with "integrations" in feedback messages

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.1%. Comparing base (45942c7) to head (3e0a1f6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5407   +/-   ##
=====================================
  Coverage   94.1%   94.1%           
=====================================
  Files        371     371           
  Lines      31542   31542           
  Branches    3380    3380           
=====================================
  Hits       29691   29691           
  Misses      1200    1200           
  Partials     651     651           

[lcouzens]

/retest

[lcouzens]

/retest