Revert^2 "Disable from-text stub build for sdk products"

This change introduces `PRODUCT_BUILD_FROM_SOURCE_STUB` product
variable, which is set to true for sdk targets.

This change resubmits https://r.android.com/2834692.

Test: m TARGET_PRODUCT=sdk TARGET_RELEASE=trunk_staging sdk and inspect ninja query to verify that stubs are built from source
Bug: 311203379
Change-Id: I7d9f833ae76ceabbf2ce4df0141688e24ea164c8