Add more tests to Metric SDK aggregation

[cijothomas]

Adding more tests to test meter and instrument identify part, and whether they get merged or not.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 67.3%. Comparing base (d5bf258) to head (d1f2ae8).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1600     +/-   ##
=======================================
+ Coverage   67.0%   67.3%   +0.3%     
=======================================
  Files        138     138             
  Lines      19479   19654    +175     
=======================================
+ Hits       13058   13243    +185     
+ Misses      6421    6411     -10     

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