Fix: display_name should not exclude the default catalog when environment_suffix_target is set to CATALOG

[erindru]

Prior to this, when using environment_suffix_target: catalog against a model in the default catalog, the CLI would give output like:

$ sqlmesh plan erin
...SNIP...
Models needing backfill:
└── none__erin.sqlmesh_example.incremental_model: [2020-01-01 - 2025-04-07]
Apply - Backfill Tables [y/n]: y

This was due to an output optimisation where we hid the catalog as unnecessary information if it matched the default catalog.

However, environment_suffix_target: catalog relies on the default catalog being present because it needs it to generate the catalog name for the virtual environment.

This PR fixes the output:

$ sqlmesh plan erin
...SNIP...
Models needing backfill:
└── tobiko-1__erin.sqlmesh_example.incremental_model: [2020-01-01 - 2025-04-07]
Apply - Backfill Tables [y/n]: y

Note that this was a display-only issue, the SQL queries being executed in the background still contained the correct catalog