[omnibox][grouping] Timing histograms `UpdateResult()` & `SortAndCull()`

Add microsecond scoped timing histograms for the 2 methods. The grouping
framework is likely to slow these down, and we want to ensure the
regression is acceptable. Likewise, they'll help verify any
optimizations we do are effective.

Current testing shows the grouping framework is 2-5x slower than the
traditional grouping; which isn't surprising because the traidtional
grouping is essentially merely a `std::partial_sort()` while the
framework initializes structs. Regardless, it's not worrisome compared
to the overall omnibox latency (10-50 us compared to 1-100 ms).

Bug: 1343512
Change-Id: I4a3603c4bb9b866e776369c445039caeb6d280d2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4123231
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1086623}