Fix the logic to detect AzureNetworkContainer.exe

[ashvindeodhar]

AzureNetworkContainer.exe is in the same location as azure-cns.exe but
if CNS is invoked from a process which is in a different working directory,
os.stat called in CNS points to the directory of parent process. This change
fixes the logic to point to the correct working directory.

What this PR does / why we need it:

Which issue this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close that issue when PR gets merged): fixes #

Special notes for your reviewer:

Release note:

[codecov]

Codecov Report

Merging #440 into master will decrease coverage by 0.66%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #440      +/-   ##
==========================================
- Coverage   53.32%   52.66%   -0.67%     
==========================================
  Files          28       28              
  Lines        4032     4022      -10     
==========================================
- Hits         2150     2118      -32     
- Misses       1610     1631      +21     
- Partials      272      273       +1

Impacted Files	Coverage Δ
npm/translatePolicy.go	88.01% <0%> (-3.06%)	⬇️
npm/pod.go	64.13% <0%> (+1.2%)	⬆️

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[tamilmani1989]

discussed offline. lgtm