📈 Add rule and sample app around clean testing best practices

[danielmackay]

Currently with integration testing we are using both Respawn and Test Containers to create and reset our databases.

Tasks

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1. Create a rule that provides guidance on when to use respawn vs a new test container
2. The rule should take performance into account
3. Create a sample repo to demonstrate the approach
4. Add the sample repo to the awesome-ca repo