In both onImageRead and onImageWrite, there's a call to
endRenderPassAndGetCommandBuffer when necessary to record a command.
There was an extraneous call to endRenderPass in both functions for no
good reason.

Bug: angleproject:4882
Change-Id: I8f3b18dbb3cb9a8b92dedcc603eaf44b1e485986
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2323642Reviewed-by: Tim Van Patten <timvp@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>