gpu: Reduce post processing already done on CPU #9464

Job	Run time
code-format	34s
check_vvl	1m 7s
androidOnLinux	5m 24s
linux (address sanitizer, debug, robinhood ON )	26m 50s
linux (address sanitizer, release, robinhood ON )	16m 31s
chromium (target_os="linux" target_cpu="x64")	8m 4s
android (arm64-v8a, ON, c++_shared)	13m 11s
linux (thread sanitizer, release, robinhood ON )	2h 33m 1s
chromium (target_os="android" target_cpu="arm64")	10m 35s
android (armeabi-v7a, OFF, c++_static)	9m 7s
Ubuntu Backcompat	9m 32s
linux (address sanitizer, release, robinhood OFF )	19m 0s
mingw	7m 8s
windows (amd64)	10m 22s
windows (amd64_x86)	9m 46s
iOS	4m 57s
windowsUpload	0s
androidUpload	0s
linux Upload	0s
	5h 5m 9s

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