Added correct exception handling for discovery of Metadata apis

[danielsagi]

Description

Following #486 There seems to be an exception risen when requesting AWS metadata server when running under GKE clusters. For some reason exception handling there was lacking, and caught only connection timeout Exceptions.

Now added general except for all metadata api discoveries.

Fixed Issues

Fixes #486

Contribution checklist

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

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[codecov[bot]]

Codecov Report

Merging #488 (d513aa7) into main (00eb0df) will increase coverage by 0.08%. The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main     #488      +/-   ##
==========================================
+ Coverage   64.68%   64.76%   +0.08%     
==========================================
  Files          46       46              
  Lines        2509     2512       +3     
==========================================
+ Hits         1623     1627       +4     
+ Misses        886      885       -1     

Impacted Files	Coverage Δ
kube_hunter/modules/discovery/hosts.py	54.01% <50.00%> (+0.74%)	:arrow_up:
kube_hunter/core/events/handler.py	90.13% <0.00%> (+0.65%)	:arrow_up:

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