Created Timestamp: Optimize memory use for OM Text CT parsing (with `created-timestamp-zero-ingestion` feature flag)

[bwplotka]

Proposal

As observed accidently on main and without any feature flag we use a lot of memory for CreatedTimestamp call for OM text. This is .due to deep coping of parser on every CreatedTimestamp, so technically per every series (!). This was a known naive implementation we decided to accept when iterating on this feature in #14356

This issue is to minimize that memory use. We already discussed this, but to put it here:

• We should see if we can reuse existing parser (not copy it).
• If we have to copy, copy once and reuse a second parser (e.g. reset it's positions).

Acceptance Criteria

• The additional memory use per OM Text scrape with CT feature is minimal (~within +5% max)

All of this is a good lesson and argument to improve OM Text format in 2.0 (:

Related to #14217

[beorn7]

Hello from the bug scrub!

Work seems to be ongoing on the syntax change, which seems to be a prerequisite for this.

Leaving open.