java/util/ArrayList/Bug8146568.java and j/u/Vector/Bug8148174.java use @ignore w/o bug-id

java/util/ArrayList/Bug8146568.java and java/util/Vector/Bug8148174.java have '@ignore This test has huge memory requirements', canonically, @ignore should be followed by the id of the bug which describes the problem and will be used to eventually fix it.

note: the requirement of 17Gb memory should be expressed via '@requires os.maxMemory > 17G'.
if a test execution time is too long for it to be run in regular/automated test execution, the more appropriate way to express this is '/manual' option which excludes a test from automated execution, yet still allows one to run it.