Vulkan: Remove unnecessary pipeline library retain Vertex input and fragment output partial pipelines are kept alive until context destruction, so there's no need to retain them. Bug: angleproject:7369 Change-Id: I8cbe5b9f70845bb5d9348f11889f64a6a94a6b87 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4100407 Auto-Submit: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>