Simpler Runner

[dgageot]

Another extract of #1204

• Simplify the code that unmutes logs
• Fix logrus usage

[codecov-io]

Codecov Report

Merging #1304 into master will decrease coverage by 0.02%.
The diff coverage is 42.85%.

@@            Coverage Diff             @@
##           master    #1304      +/-   ##
==========================================
- Coverage   44.54%   44.51%   -0.03%     
==========================================
  Files         103      103              
  Lines        4598     4596       -2     
==========================================
- Hits         2048     2046       -2     
  Misses       2343     2343              
  Partials      207      207

Impacted Files	Coverage Δ
pkg/skaffold/runner/runner.go	48.17% <42.85%> (-0.42%)	⬇️

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