Reland align boot jar exclusion with apex_contributions

This relands https://r.android.com/3063301 alongside a Soong CL that
updates the bootclasspath_fragment content validation code.

Bug: 328578801
Test: m nothing --no-skip-soong-tests
Change-Id: Ifa894d4e3270829ff69669e1a914cdea8d7fb03f