Add ES autoprovisioning CR metric

[rubenvp8510]

Signed-off-by: Ruben Vargas ruben.vp8510@gmail.com

Which problem is this PR solving?

• Added metric that determines the amount of CRs using autoprovisioned Elasticsearch storage.

[codecov]

Codecov Report

Merging #1728 (f1dec99) into master (b415094) will increase coverage by 0.02%.
The diff coverage is 84.61%.

❗ Current head f1dec99 differs from pull request most recent head 816a110. Consider uploading reports for the commit 816a110 to get more accurate results

@@            Coverage Diff             @@
##           master    #1728      +/-   ##
==========================================
+ Coverage   87.43%   87.46%   +0.02%     
==========================================
  Files          99       99              
  Lines        5914     5926      +12     
==========================================
+ Hits         5171     5183      +12     
  Misses        570      570              
  Partials      173      173              

Impacted Files	Coverage Δ
pkg/metrics/instances.go	89.36% <84.61%> (+1.55%)	⬆️

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