Setting cron as an expression without a start value causes virtual layer update fail when trying to create a view pointing to a non-existent table

[tchopper]

A model with:

`
MODEL (
name full_model_using_cron_expression,
kind FULL,
cron '20 8 * * *',
);

SELECT
1 as id,
'test data' as value
`

Using an execution timestamp execution_time = 2024-01-02 01:49:00+00:00.

Will fail with:

Execution failed for node SnapshotId<"full_model_using_cron_expression": 2815714217>

It skips the physical table creation - however still attempts to point a view to it.

However, setting the model with a start value of say '2024-01-01' - will correctly execute. Same goes for setting the cron expression to @daily. I've run into this one in prod twice now.

Upon further inspection - it seems related to how the missing intervals backfill works.

If a model is new - a snapshot should be created regardless and the cron should be ignored? - I'll create a PR shortly which enforces this behaviour.