De-duplication of Elastic vs OTel source of data

[SergeyKleyman]

With OTel -> Elastic bridge implemented for some use cases there will be two sources of spans: for example for PDO there is OTel instrumentation and Elastic legacy instrumentation. We would like to avoid producing two spans for each PDO call instrumented by both OTel and Elastic.

Implementation notes:

• Possible approach: Mark some spans as leaf (for example PDO and curl) and not create any OTel bridge generated spans under the "leaf" spans