Vulkan: Fix descriptorSet perf counter values. Some counters were getting reset in multiple places, which could result in queries returning zero counts. Fix this by consolidating per-frame counter resets. Also updates how we compute cache hit/miss counters. This results in correct and consistent counts for cache accesses. Also includes a fix to not update the overlay when there are no enabled widgets. Also does away with some of the object- specific perf counters that were made to track descriptor set allocations. Bug: angleproject:6776 Change-Id: I769c715986defc50f0cfd0d997c338d34174e9f0 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3573389 Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Yuxin Hu <yuxinhu@google.com> Commit-Queue: Jamie Madill <jmadill@chromium.org>