dexpreopt rules for google mainline prebuilts with missing source

AddFarVariationDependencies runs into issues in partner workspaces which
do not contain the sources of google mainline prebuilts, since the
prebuilt would be renamed in a prior prebuilt_rename mutator. To account
for this rename, add `prebuilt_` prefix in
`addDependenciesOntoSelectedBootImageApexes` to ensure that the prebuilt
apex does not get elided

Test: m nothing --no-skip-soong-tests
Test: in v-aml-prebuilt dev,
aninja -t query out/soong/dexpreopt_arm64/dex_bootjars_input/okhttp.jar | head -n3
out/soong/dexpreopt_arm64/dex_bootjars_input/okhttp.jar:
  input: g.android.Cp
    out/soong/.intermediates/vendor/partner_modules/ArtPrebuilt/prebuilt_com.google.android.art_compressed.deapexer/android_common/deapexer/javalib/okhttp.jar
(uses the prebuilt deapexed boot jar, and no the source apex boot jar)

Bug: 362163831
Change-Id: Ie94a36911ab40ac09a470efe505fd00ef3a5bf9c