feat(instrumentation-pg): add operation name attribute to db duration metric

[maryliag]

Which problem is this PR solving?

• Part Of Prototype for Semantic Conventions for Database Metrics #2348

Short description of the changes

• Add the required attribute of operation name. This PR uses the same function already being used to name the span with the operation name

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.74%. Comparing base (a558044) to head (468e8cb).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2475   +/-   ##
=======================================
  Coverage   90.74%   90.74%           
=======================================
  Files         156      156           
  Lines        7725     7728    +3     
  Branches     1588     1590    +2     
=======================================
+ Hits         7010     7013    +3     
  Misses        715      715           

Files with missing lines	Coverage Δ
...elemetry-instrumentation-pg/src/instrumentation.ts	89.83% <100.00%> (+0.17%)	⬆️
...node/opentelemetry-instrumentation-pg/src/utils.ts	97.63% <100.00%> (ø)