in_opentelemetry: change endpoints for metrics/traces and fix trace serialization
in_opentelemetry: change endpoints for metrics/traces and fix trace serialization

this patch implements two changes:

 1. use new OTLP exporter URI endpoints:

    - metrics -> /v1/metrics
    - traces  -> /v1/traces

 2. Traces packaging

    When receiving raw traces as JSON, now the patch forces the detection
    of the object type, if is a map ({...}), now the content is appended
    directly, in the opposite case where the payload is something different
    it keeps the old behavior to set the record structure as:

    {"trace": <THE PAYLOAD>}

Signed-off-by: Eduardo Silva <81f705dc2ce1a61a2621e0e4b442a9474e1d0c70@calyptia.com>

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