(DE-598) feat(dbt): load backend sources as snapshots

[LucileRainteau]

DE PR

Describe your changes

Please include a summary of the changes:

This PR [adds/removes/fixes/replaces] the [feature/bug/etc].

Tag a reviewer if necessacy @github/username

Jira ticket number and/or notion link

JIRA-ticket_number

Type of change

• Fix (non-breaking change which corrects expected behavior)
• New fields (non-breaking change)
• New table (non-breaking change)
• Concept change (potentially breaking change which modifies fields according to new or evolving business concepts)
• Table deletion (potentially breaking change which adds functionality/ table)

Checklist before requesting a review

• I have performed a self-review of my code
• My code passes CI/CD tests
• I updated README.md
• I have updated the dag
• If my changes concern incremental table, I have altered their schema to accomodate with field's creation/deletion
• I have made corresponding changes to the tables documentation
• I have made corresponding changes to the fields glossary
• I will create a review on slack and ensure to specify the duration of the review task: short (<10min), medium (<30min), long (>30min)

Added tests?

• 👍 yes
• 🙅 no, because they aren't needed
• 🙋 no, because I need help
• ⏰ no, but I created a ticket

[valoumiaou]

t'as essayé sans les ""
et sinon set la variable en début de model:
{% conn_id = env_var('APPLICATIVE_EXTERNAL_CONNECTION_ID')%}