stats/otel: upgrade grpc in go.mod to use version that contains the experimental/stats

[arvindbr8]

Building stats/otel was broken on its own because this package depends on grpc/experimental/stats which is not released yet. Our tests passed because of the replace directive magic.

RELEASE NOTES: none

[codecov[bot]]

Codecov Report

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

Project coverage is 81.84%. Comparing base (9ab8b62) to head (07f84df). Report is 13 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7545      +/-   ##
==========================================
- Coverage   81.93%   81.84%   -0.10%     
==========================================
  Files         362      361       -1     
  Lines       27831    27825       -6     
==========================================
- Hits        22803    22773      -30     
- Misses       3832     3854      +22     
- Partials     1196     1198       +2     

see 25 files with indirect coverage changes