fix: Use ExtraHosts only for linux machines with native docker engine

[MortalHappiness]

TL;DR

Use ExtraHosts only for Linux machines with native docker engine

Type

• [x] Bug Fix
• [ ] Feature
• [ ] Plugin

Are all requirements met?

• [x] Code completed
• [x] Smoke tested
• [x] Unit tests added
• [x] Code documentation added
• [x] Any pending items have an associated Issue

Complete description

Detect whether /var/run/docker.sock is not a symbolic link and is a socket file. If true, add ExtraHosts. Otherwise, return empty ExtraHosts.

Tracking Issue

None

Follow-up issue

NA

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (9c87165) 67.69% compared to head (878526f) 67.71%.

:exclamation: Current head 878526f differs from pull request most recent head 7c83a52. Consider uploading reports for the commit 7c83a52 to get more accurate results

Files	Patch %	Lines
pkg/docker/docker_util.go	88.88%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #461      +/-   ##
==========================================
+ Coverage   67.69%   67.71%   +0.02%     
==========================================
  Files         148      148              
  Lines        6639     6647       +8     
==========================================
+ Hits         4494     4501       +7     
- Misses       1855     1856       +1     
  Partials      290      290              

Flag	Coverage Δ
unittests	67.71% <88.88%> (+0.02%)	:arrow_up:

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