Original PR description

**Description of the issue/feature this PR addresses**  
The `block_tab` test module was previously located within the `website/builder` test suite, causing unnecessary dependencies when testing `html_builder`.  
Additionally, test snippet setups within `block_tab` were inconsistent across the suite and difficult to read or maintain.

**Current behavior before PR**  
- `block_tab` tests are part of the `website/builder` test suite.  
- Running `html_builder` tests requires loading website-related dependencies.  
- Test snippet setup varies between tests and is harder to follow.

**Desired behavior after PR is merged**  
- `block_tab` tests are moved into the `html_builder` test suite.  
- `html_builder` can be tested independently without `website` dependencies.  
- Test snippet setup is standardized via a flexible helper, making it easier to implement and read.


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