Revert^2 "Package dexpreopt artifacts for libcore jars in the ART apex."

This reverts commit 24babe3a.

Build failures are fixed after reworking the patch:

  - 'missing dependencies' on aosp-master-art branch is fixed by
    disabling profile generation in case default profile is not
    found (it is part of framework absent in aosp-master-art)

  - invalid dex2oat invocation should no longer happen after
    disabling dexpreopt on targets that do not use default ART config
    (fixed in CL If2d4fe2cdcb6a81c7c6d730d18c2b681a74fb0b7)

Dexpreopt artifacts for the libcore part of the boot class path are
now packaged in the ART apex. The system image still contains
dexpreopt artifacts for the full set of boot class path libraries
(both libcore and framework); the libcore part will be removed and
boot image extension will be used in a follow-up CL.

Since this is specific to the ART apex and makes no sense for other
apexes, the implementation adds a boolean flag "is ART apex" rather
than a new apex module property.

Build rules for the new set of dexpreopt artifacts are created using
a new variant of the global boot image config. Previously we had two
variants: "default" (for the system image) and "apex" (for the
JIT-zygote experiment). This patch adds a third "art" variant.

Bug: 143594594
Bug: 143593500

Test: m
Test: m com.android.art deapexer \
    && find $ANDROID_BUILD_TOP -type f -name 'com.android.art.*.apex \
        | xargs deapexer | grep boot \
    Expect to find javalib/$ARCH/boot*.{art,oat,vdex} files.
Test: m art/build/apex/runtests.sh

Change-Id: Ib37acaec8401bd23c8d547dadf773565406ef448