Refactor (Tests) - Use DbTestCase instead of TestCase

[RomainLvr]

Checklist before requesting a review

Please delete options that are not relevant.

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• I have updated the CHANGELOG with a short functional description of the fix or new feature.
• This change requires a documentation update.

Description

Replace legacy add() and update() calls with createItem() and updateItem()
helper methods across all escalade test files. Standardize configuration
initialization using initConfig() method from EscaladeTestCase.

[RomainLvr]

ping @stonebuzz