Increase the memory allocation for acceptance tests to 512m
Increase the memory allocation for acceptance tests to 512m

This is needed because UploadArchiveIT#verifyUploadArchiveFormats uses a
lot of heap space memory and causes the CI to fail the Build/Tests
check. Change I3f87f322e1 is reducing the memory for that test but
requires a change in JGIT. We increase the memory in this change to
unblock the failing CI jobs.

Bug: Issue 13970
Change-Id: I447599aff61d557f9b6446e488fe73c78bdcab6a

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