Make gateway discovery always run when running as pod

[danielsagi]

The old method was to check if we can access metadata api, if so, we extracted a subnet from it and only scanned this subnet This made us sometimes miss important internal kuberentes components.

Metadata api discovery should only be as a bonus, and we should rely on gateway discovery.

This PR also adds more verbose debug output when discovering aws metadata.

Fixed Issues

fixes #467

Contribution checklist

• [x] I have read the Contributing Guidelines.
• [x] The commits refer to an active issue in the repository.
• [x] I have added automated testing to cover this case.

[codecov[bot]]

Codecov Report

Merging #471 (6808adf) into main (f67f082) will increase coverage by 0.02%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #471      +/-   ##
==========================================
+ Coverage   63.86%   63.88%   +0.02%     
==========================================
  Files          43       43              
  Lines        2424     2431       +7     
==========================================
+ Hits         1548     1553       +5     
- Misses        876      878       +2     

Impacted Files	Coverage Δ
kube_hunter/modules/discovery/hosts.py	53.26% <0.00%> (-2.11%)	:arrow_down:
kube_hunter/core/events/handler.py	89.86% <0.00%> (-0.68%)	:arrow_down:
kube_hunter/modules/hunting/apiserver.py	72.34% <0.00%> (+1.92%)	:arrow_up:

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