Revert to jsonpb to test theory about binary size

[bogdandrutu]

Try dropping jsoniter deps to see binary size improvement. Looks like about 1.5MiB improvement.

Before:

ls -la bin/otelcorecol_darwin_arm64
-rwxr-xr-x@ 1 bdrutu  staff  42268226 Jul 10 05:47 bin/otelcorecol_darwin_arm64

After:

ls -la bin/otelcorecol_darwin_arm64 
-rwxr-xr-x@ 1 bdrutu  staff  40598354 Jul 17 13:23 bin/otelcorecol_darwin_arm64

[codecov]

Codecov Report

Attention: Patch coverage is 93.33333% with 2 lines in your changes missing coverage. Please review.

Please upload report for BASE (main@6334c5b). Learn more about missing BASE report.
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pdata/pmetric/json.go	66.66%	1 Missing and 1 partial ⚠️

❌ Your patch check has failed because the patch coverage (93.33%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #13373   +/-   ##
=======================================
  Coverage        ?   91.20%           
=======================================
  Files           ?      523           
  Lines           ?    28415           
  Branches        ?        0           
=======================================
  Hits            ?    25917           
  Misses          ?     1967           
  Partials        ?      531           

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