Consolidate ArrayUtilsTest into one file

Commit 35402eb8 ("Move tests for com.android.internal.util out of
coretests") intentionally moved ArrayUtilsTest from coretests into
utiltests, but commit 082614c6 ("Cache per-Activity Resources
objects") immediately added the file back with some new test cases only.
This appears to have been a rebase error, as these commits went in at
about the same time.  The result is that there are two ArrayUtilsTest
files, which is confusing.  Fix this by moving the coretests test cases
into utiltests.

Test: atest com.android.internal.util.ArrayUtilsTest
Change-Id: If410c6e15b7169843aae204ee7ae7301e6a64401