fix: do not fetch oauth2 from konnect

[czeslavo]

Summary

As Konnect does not support OAuth2 credentials, we should not try to fetch them when dumping config (currently it returns 404s that are ignored).

Issues resolved

Part of Kong/kubernetes-ingress-controller#6240.

[CLAassistant]

All committers have signed the CLA.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 20.00000% with 12 lines in your changes missing coverage. Please review.

Project coverage is 42.72%. Comparing base (8de497a) to head (7e362ad).
Report is 1 commits behind head on main.

Files	Patch %	Lines
pkg/dump/dump.go	0.00%	7 Missing ⚠️
pkg/utils/types.go	0.00%	4 Missing ⚠️
pkg/file/writer.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #128      +/-   ##
==========================================
- Coverage   42.72%   42.72%   -0.01%     
==========================================
  Files          75       75              
  Lines        8819     8820       +1     
==========================================
  Hits         3768     3768              
- Misses       4587     4588       +1     
  Partials      464      464              

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