Apply ValueMap for ExpoHistogram metric

[fraillt]

Most metrics has optimized measure phase by using ValueMap. However ExpoHistogram has it's own implementations.
This implementation is not only lacking performance improvements, but also some important functionality (e.g. there's no check for is_under_cardinality_limit).

In order to proceed with this, we need:

• update ValueMap to provide interface that will allow to implement ExpoHistogram efficiently ValueMap interface change #2117
• introduce convenient functions for collecting data points Unify metrics DataPoints collection #2145