Added config option for disabling iptable lock

[tamilmani1989]

What this PR does / why we need it:
Added config option for disabling iptable lock. By default, iptable lock is enabled. If users want to disable iptable lock, they have to set disableIPTableLock field to true in conflist.

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 #470 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #470      +/-   ##
==========================================
- Coverage   52.74%   52.71%   -0.03%     
==========================================
  Files          28       28              
  Lines        4224     4215       -9     
==========================================
- Hits         2228     2222       -6     
+ Misses       1724     1723       -1     
+ Partials      272      270       -2

Impacted Files	Coverage Δ
npm/translatePolicy.go	80.41% <0%> (-0.12%)	⬇️
npm/iptm/iptm.go	59.6% <0%> (+0.7%)	⬆️

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[chandanAggarwal]

[ninzavivek]

In my opinion, we should update the conflist also. But it is upto you. I understand that it is workaround for short time, but change looks incomplete.

[tamilmani1989]

In my opinion, we should update the conflist also. But it is upto you. I understand that it is workaround for short time, but change looks incomplete.

By default iptable lock is enabled. Even if we specify this in conflist, they have to manually flip the flag before rollout. I don't want to expose this to user to disable it unless there is a need.