feat: etcd metrics URL

[jackfrancis]

Reason for Change:

This PR adds the --listen-metrics-urls option to the etcd runtime configuration for prometheus metrics scraping.

Issue Fixed:

Fixes #2171

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[codecov]

Codecov Report

Merging #2989 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #2989   +/-   ##
=======================================
  Coverage   72.07%   72.07%           
=======================================
  Files         141      141           
  Lines       26184    26190    +6     
=======================================
+ Hits        18871    18877    +6     
  Misses       6219     6219           
  Partials     1094     1094           

Impacted Files	Coverage Δ
pkg/engine/templates_generated.go	31.69% <ø> (ø)
pkg/engine/armvariables.go	87.44% <100.00%> (+0.16%)	⬆️

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[mboersma]

/lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jackfrancis, mboersma

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