chore: Remove deprecated 'NewScheduler' func

[matzew]

Proposed Changes

• removing a func that was deprecated since a couple of releases

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Docs

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: matzew

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• pkg/scheduler/OWNERS [matzew]

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[matzew]

/assign @pierDipi

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.12% 🎉

Comparison is base (10e25b9) 77.63% compared to head (e1f5284) 77.75%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7221      +/-   ##
==========================================
+ Coverage   77.63%   77.75%   +0.12%     
==========================================
  Files         246      246              
  Lines       13301    13284      -17     
==========================================
+ Hits        10326    10329       +3     
+ Misses       2452     2433      -19     
+ Partials      523      522       -1     

Files Changed	Coverage Δ
pkg/scheduler/statefulset/scheduler.go	74.85% <ø> (+2.41%)	⬆️

... and 1 file with indirect coverage changes

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[matzew]

/test upgrade-tests

[creydr]

/retest

[creydr]

/lgtm