Set Docker open-files limit ( 'ulimit -n') to be consistent with other runtimes

[tstromberg]

Work in progress, designed to fix #5751

Unfortunately, there did not appear to be a viable approach that does not involve programming each container runtime. Thankfully, it seems like only Docker diverged.

[tstromberg]

/ok-to-test

[k8s-ci-robot]

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[codecov-io]

Codecov Report

Merging #5761 into master will decrease coverage by 0.04%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #5761      +/-   ##
==========================================
- Coverage   37.86%   37.81%   -0.05%     
==========================================
  Files         106      106              
  Lines        7796     7806      +10     
==========================================
  Hits         2952     2952              
- Misses       4464     4475      +11     
+ Partials      380      379       -1

Impacted Files	Coverage Δ
cmd/minikube/cmd/service.go	21.21% <0%> (-4.72%)	⬇️
cmd/minikube/cmd/config/open.go	13.46% <0%> (-1.76%)	⬇️
pkg/minikube/service/service.go	77% <0%> (+0.81%)	⬆️