The patch refactors cases that test a uniform block only containing
a large array member, which will be translated to StructuredBuffer
on D3D backend.

Bug: angleproject:3682
Change-Id: I3170a4c82896ce8895909db87c70b80656300383
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2489482
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Jiajia Qin <jiajia.qin@intel.com>