fix(azure): add new way to auth against App Insight

[puchy22]

Context

In check app_function_application_insights_enabled was missing the APPLICATIONINSIGHTS_CONNECTION_STRING to connect Application functions and App Insights.

Fix #7298

Description

• Check the APPLICATIONINSIGHTS_CONNECTION_STRING configuration
• Remove the check if the AppInishgt exists in same subscription due to false positives
• Remove all related with AppInishgt service in tests

Checklist

• Are there new checks included in this PR? Yes / No
  • If so, do we need to update permissions for the provider? Please review this carefully.
• Review if the code is being covered by tests.
• Review if code is being documented following this specification https://github.com/google/styleguide/blob/gh-pages/pyguide.md#38-comments-and-docstrings
• Review if backport is needed.
• Review if is needed to change the Readme.md
• Ensure new entries are added to CHANGELOG.md, if applicable.

API

• Verify if API specs need to be regenerated.
• Check if version updates are required (e.g., specs, Poetry, etc.).
• Ensure new entries are added to CHANGELOG.md, if applicable.

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.31%. Comparing base (f254a4b) to head (0df5985).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7763      +/-   ##
==========================================
- Coverage   81.31%   81.31%   -0.01%     
==========================================
  Files         258      258              
  Lines        9269     9268       -1     
==========================================
- Hits         7537     7536       -1     
  Misses       1732     1732              

Flag	Coverage Δ
prowler	81.31% <ø> (-0.01%)	⬇️

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Components	Coverage Δ
prowler	81.31% <ø> (-0.01%)	⬇️
api	∅ <ø> (∅)

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