Span ID always null in Logs | Logs ID injection

**Describe the bug**: I am using logging support which injects correlation ids (trace, transaction, span). However even after running with 100% sample rate I've not been able to get a single log with a Span ID!
Also "maybe" this could be the reason that I am not seeing any logs in trace waterfall

**To Reproduce**

1. Install elastic apm agent version
2. Simply allow logging integration (default)
3. Check in your APM

**Environment (please complete the following information)**
- OS: Linux and Mac
- Python version: 3.9/10
- Framework and version [e.g. Django 2.1]: Should not matter but Sanic v22
- APM Server version: Proprietary Solution
- Agent version: `elastic-apm==6.7.1`

**Additional context**
N/A

Inizia riproducendo il problema con elastic-apm==6.7.1, Python 3.9 o 3.10 e Sanic v22, con l'integrazione di logging predefinita abilitata. Esamina l'integrazione di logging e la gestione del contesto di trace per determinare perché Span ID rimane null, quindi verifica che i log emessi lo contengano e valuta se compaiono voci di trace waterfall.

Scritto dal modello di indicizzazione a partire dal testo della issue.