Revert "[release/3.0] Move corefx to stages, use arcade's package artifacts convention"

[safern]

Reverts #40198

Reverting as it broke the official build:

Stage validate depends on unknown stage build.
Stage Publish depends on stage validate which creates a cycle in the dependency graph.
Stage PublishValidation depends on stage Publish which creates a cycle in the dependency graph.
Stage PVR_Publish depends on stage validate which creates a cycle in the dependency graph.
Stage PVR_PublishValidation depends on stage PVR_Publish which creates a cycle in the dependency graph.
Stage PubRel_Publish depends on stage validate which creates a cycle in the dependency graph.
Stage PubRel_PublishValidation depends on stage PubRel_Publish which creates a cycle in the dependency graph.
Stage IS_Publish depends on stage validate which creates a cycle in the dependency graph.
Stage IS_PublishValidation depends on stage IS_Publish which creates a cycle in the dependency graph.

cc: @ViktorHofer