Excessive memory allocation in OTel broker metrics

[asafm]

          @dragosvictor @merlimat Please note this contradicts all the work done to eliminate memory allocation. 

The Attributes for each topic should be persisted either in a Map or easier by saving it in the implementation of Topic interface you're getting. Then you simply retrieve it by topic.getTopicOTelAttributes().
When you are not doing it, you are creating a memory allocation each time you run collect, for each topic. This is exactly what I was set out to avoid in the whole implementation rework of OpenTelemetry Java SDK memory mode.

Originally posted by @asafm in #22467 (comment)

[asafm]

@dragosvictor Can you please take a look?
@eolivelli

[lhotari]

Fixed by #22837

[dragosvictor]

@lhotari Working on the same improvement for the topic stats, can you please reopen this?