Remove the ability to install boot images by bootclasspath_fragments.

We don't need this anymore because we are going to compile ART jars and
framework jars together.

Bug: 280776428
Test: m
(cherry picked from https://android-review.googlesource.com/q/commit:b47caccbc037b65462f757c462a99732ad6dd51c)
Merged-In: I070157530449a1bb5779e25984c367df3dde7b36
Change-Id: I070157530449a1bb5779e25984c367df3dde7b36