Switch usages of legacy-test to android.test.base

The legacy-test library has been deprecated in favour of the
android.test.base library which will be exposed to developers in
similar manner to android.test.runner and android.test.mock.

Bug: 30188076
Test: make checkbuild && make droid && flash
Change-Id: I36a9ccf8a1b4b7b75ce1ca4893daa3db6e660b30

core/tasks/check_boot_jars/package_whitelist.txt

@@ -121,7 +121,7 @@ com\.android\..*
 
 
 ###################################################
-# legacy-test.jar
+# android.test.base.jar
 junit\.extensions
 junit\.framework
 android\.test