feat(cardinality): Track exceeded CardinalityLimit for each bucket

[loewenheim]

Fixes #3806.

Outcome::CardinalityLimited now contains the IDs of the CardinalityLimits that were exceeded. We use a SmallVec<[String; 4]> for this (4 chosen essentially at random—please advise on what a sensible number would be here).

We track which cardinality limits are exceeded by a bucket in DefaultReporter. This tracking propagates through CardinalityLimits to CardinalityLimitsSplit, which gains a new field exceeded_limits. Finally, in cardinality_limit_buckets, we now call track with each bucket individually—each of them has a different outcome with different exceeded limits, so it's not possible to do this in bulk.

[loewenheim]

Update: we now only store one limit per CardinalityLimit outcome, for implementation simplicity. It's expected to be the most common case anyway.