[5.5] Revert PR #22222 breaking change

[themsaid]

This causes troubles while comparing models in tests, assertEquals($model, $another) where one model is recently created while the other is loaded from a relationship, the one recently created will have the getTable called and setTable will set the table, while the one retrieved will have $table = null causing the comparison to fail.

Original PR: https://github.com/laravel/framework/pull/22222/files

Check #22409 for reference