Move the logic for creating APEX-related symlinks

The existing location of logic for creating symlinks to files that have
moved into APEX does not get executed for -user builds, only
-userdebug and -eng. The new location is equally arbitrary but appears
to be invoked for -user, -userdebug and -eng targets.

Tested with:
make cleaninstall && lunch taimen-[user|userdebug|eng] && make droid

Inspected:
ls -l out/target/product/taimen/system/usr/icu

Bug: 128249030
Bug: 122985829
Bug: 124106384
Test: see above
Merged-In: I92a52d0b5ef97e8cb4f780691f8594e40f2fa6b3
Change-Id: I92a52d0b5ef97e8cb4f780691f8594e40f2fa6b3
(cherry picked from commit 0ed52b78)