Remove useless command line flag

[dgageot]

This is yet another piece of #1204 that I'm breaking into pieces to make it easier to rebase and review.

This PR removes a command line flag that doesn't make sense

Signed-off-by: David Gageot david@gageot.net

[codecov-io]

Codecov Report

Merging #1292 into master will increase coverage by 0.03%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master    #1292      +/-   ##
==========================================
+ Coverage   44.24%   44.28%   +0.03%     
==========================================
  Files         104      104              
  Lines        4629     4625       -4     
==========================================
  Hits         2048     2048              
+ Misses       2372     2368       -4     
  Partials      209      209

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/deploy.go	0% <0%> (ø)	⬆️

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