SNOW-964608: Fix response handling for auth_okta

[sfc-gh-pbulawa]

Description

Fix response handling in auth_okta as the axios v.1.6.0 returns it differently than previous one.

Checklist

• Format code according to the existing code style (run npm run lint:check -- CHANGED_FILES and fix problems in changed code)
• Create tests which fail without the change (if possible)
• Make all tests (unit and integration) pass (npm run test:unit and npm run test:integration)
• Extend the README / documentation and ensure is properly displayed (if necessary)
• Provide JIRA issue id (if possible) or GitHub issue id in commit message

[codecov]

Codecov Report

Merging #693 (faedff3) into master (645faeb) will increase coverage by 0.41%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #693      +/-   ##
==========================================
+ Coverage   87.33%   87.75%   +0.41%     
==========================================
  Files          61       61              
  Lines        5756     5756              
==========================================
+ Hits         5027     5051      +24     
+ Misses        729      705      -24     

Files	Coverage Δ
lib/authentication/auth_okta.js	87.27% <100.00%> (ø)

... and 8 files with indirect coverage changes

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