Use STL container for vulkan memory allocator There is a crash related to VMA containers, so switch to STL containers to see if it can workaround the issue. Bug: chromium:1266412 Change-Id: I8416e4b4a27588ac2d710a4ef7600cd91b080535 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3327744 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: Peng Huang <penghuang@chromium.org>