feat(celery): Enable sending the sent task event by default

[adinhodovic]

Description

Enable sending task sent event by default. It's useful for e.g Flower and Celery-exporter.

Checklist:

• I've made sure that tests are updated accordingly (especially if adding or updating a template option)
• I've updated the documentation or confirm that my change doesn't require any updates

Rationale

Helps differ between sent to workers and received by them.

Forgot that this is disabled in previous pr.

[luzfcb]

@adinhodovic, thanks again. 🚢