tests: Make Go coverage hermetic and split live contracts

[nishantmonu51]

Make the Go coverage signal reproducible on pull requests and main.

• run the coverage and race suite in short mode against explicit product roots
• mark credentialed connector fixtures as expensive
• move live-provider contracts into a separate scheduled workflow
• compact duplicate cross-package coverage blocks before upload
• add Codecov flags and product/test-support exclusions
• retain diagnostic artifacts while uploading only complete successful profiles

Validation:

• go test -short -count=1 ./runtime -run '^TestDedicatedConnector$'
• go test -short -count=1 ./runtime/drivers/druid -run '^TestScan$'
• go test -short -count=1 ./runtime/testruntime/...
• full baseline coverage run across admin, cli, runtime, and scripts

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. No documentation update is required.
• Intend to cherry-pick into the release branch
• I am proud of this work!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 34.52%. Comparing base (595f477) to head (e7c9c86).
⚠️ Report is 406 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (595f477) and HEAD (e7c9c86). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (595f477)	HEAD (e7c9c86)
go	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #9730       +/-   ##
===========================================
- Coverage   44.98%   34.52%   -10.46%     
===========================================
  Files         726      754       +28     
  Lines       90172    93442     +3270     
===========================================
- Hits        40562    32262     -8300     
- Misses      43484    56318    +12834     
+ Partials     6126     4862     -1264     

Flag	Coverage Δ
go	?
go-hermetic	34.52% <ø> (?)

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