Vulkan: Reduce uniform block dynamic buffer size. This is to fit in the minimum required Vulkan limits that SwiftShader exposes. Bug: angleproject:3876 Bug: b/140251624 Change-Id: If1a36fc578675ebb07d3f6546689709882c174f3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1801264 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Alexis Hétu <sugoi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>