This reverts commit 134d6eed.

Reason for revert: glmark2 is unable to start on Android-Q when using ANGLE as the driver.

Original change's description:
> Vulkan: pipeline cache not populated as blob cache is not set
> 
> 1. Use vkMergePipelineCaches in eglSetBlobCacheFuncsANDROID as
>    blob cache callbacks are set after eglInititalize.
> 2. Use a more proper way to save the cache data to disk.
> 
> Bug: angleproject:3318
> Change-Id: Ieb5d10ab93e7afb2aab4446b387d7f36c878a686
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1559671
> Reviewed-by: Jamie Madill <jmadill@chromium.org>
> Commit-Queue: Jamie Madill <jmadill@chromium.org>

TBR=syoussefi@chromium.org,jmadill@chromium.org,fei.yang@arm.com

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

Bug: angleproject:3318
Change-Id: I51e49bf103142e80b2c9028b3af6d3bb58cf6348
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1683820Reviewed-by: Cody Northrop <cnorthrop@google.com>
Commit-Queue: Jamie Madill <jmadill@chromium.org>