The multi-deployer feature is not working. Remove it

[dgageot]

I'm trying to cut #1204 into pieces to make it easier to rebase and review.

This PR should, I think, be merged for the beta since it removes something that's not fully supported.

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

[codecov-io]

Codecov Report

Merging #1291 into master will increase coverage by 0.3%.
The diff coverage is 50%.

@@            Coverage Diff            @@
##           master    #1291     +/-   ##
=========================================
+ Coverage   44.24%   44.54%   +0.3%     
=========================================
  Files         104      103      -1     
  Lines        4629     4593     -36     
=========================================
- Hits         2048     2046      -2     
+ Misses       2372     2340     -32     
+ Partials      209      207      -2

Impacted Files	Coverage Δ
pkg/skaffold/runner/runner.go	48.59% <50%> (-0.22%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e3d808c...5aabf5f. Read the comment docs.

[balopat]

Agreed, LGTM