This reverts commit efb45eda.

Reason for revert: Significant perf regression on several benchmarks.
See bug for more details.

Bug: chromium:1027098

Original change's description:
> Vulkan: Accelerate Texture PBO updates
> 
> If the format of the image and the PBO match,
> use a vkCmdCopyBufferToImage transfer operation.
> 
> Test: angle_end2end_tests --gtest_filter=*PBOCompressedSubImage*
>       angle_end2end_tests --gtest_filter=*PBOWithMultipleDraws*
>       dEQP-GLES3.functional.texture.specification.tex*image*d_pbo*
> Bug: angleproject:3777
> Change-Id: I3f271024a635be113202a16f8893a199c194172d
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1906203
> Reviewed-by: Cody Northrop <cnorthrop@google.com>
> Commit-Queue: Mohan Maiya <m.maiya@samsung.com>

TBR=cnorthrop@google.com,syoussefi@chromium.org,jmadill@chromium.org,m.maiya@samsung.com,b.schade@samsung.com

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: angleproject:3777
Change-Id: I774655962e9ab5a866b9324002fb8edae8550834
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1939927Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>