Add health and metrics port mapping for placement stand-alone mode

[antontroshin]

Description

Expose healthz and metrics ports when running self-hosted with docker.
Map healthz to 58080, and metrics to 59090, to keep 5xxxx port pattern and keep 8080 and 9090 port numbers which are easier to remember what these ports are mapped to.

Issue reference

We strive to have all PR being opened based on an issue, where the problem or feature have been discussed prior to implementation.

Please reference the issue this PR will close: #800

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

• Code compiles correctly
• Created/updated tests
• Extended the documentation

[codecov]

Codecov Report

Merging #1323 (633ab2c) into master (650fd6f) will decrease coverage by 0.03%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1323      +/-   ##
==========================================
- Coverage   27.55%   27.53%   -0.03%     
==========================================
  Files          39       39              
  Lines        3912     3915       +3     
==========================================
  Hits         1078     1078              
- Misses       2757     2760       +3     
  Partials       77       77              

Files Changed	Coverage Δ
pkg/standalone/standalone.go	4.44% <0.00%> (-0.02%)	⬇️

[pravinpushkar]

can we separate them out to a const ? also same with metrics port below.

[pravinpushkar]

LGTM