[Topics] Add UMAs to help understand hanging during topics calculation

Increase the coverage of the `CalculatorResultStatus` UMA to include
the "hanging" and "terminated" state. The various hanging metrics will
be recoded if the topics calculation does not finish within 30 seconds
after start, and in this case, we won't record more metrics even if
the calculation completes afterwards.

Also, add "Started.DaysSinceSessionStart",
"Hanging.DaysSinceSessionStart" and "Hanging.SecondsSinceSessionStart"
UMAs to help understand when the hanging happens and whether/how its
distribution differs from that for topics calculations in general.

Drive-by: fix flaky test `BrowsingTopicsInternalsBrowserTest.ClassifierTab`. The test failed
once in a Dry Run, although it should be unrelated to this CL.

OBSOLETE_HISTOGRAM[BrowsingTopics.EpochTopicsCalculation.CalculatorResultStatus]=Replaced by CalculatorResultStatus2, which additionally covers the situation when the calculation is hanging or is terminated.

Bug: 332745401
Change-Id: Ied9e3ddabf6072dab7288bf76886b6fc3872210a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5421060


Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Commit-Queue: Yao Xiao <yaoxia@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1283607}