Setup a slow path/nightly build to test large tests

Right now there are ~10ish tests which are marked as ignore due to the long running time. However some of them are quite useful as they practice some extra large datasets. I suggest to setup a separate build to test them so that it's automated and prevents unexpected future bugs. Happy to help if people find it useful.

((.venv) ) ➜  rust git:(3515-test-read-logic) ✗ ack "#\[ignore"      
lance-io/tests/gcs_integration.rs
23:#[ignore = "Must be run manually on GCS"]
50:#[ignore = "Must be run manually on GCS"]

lance-encoding/src/encodings/physical/binary.rs
1092:    #[ignore] // This test is quite slow in debug mode

lance-encoding/src/encodings/physical/fixed_size_list.rs
196:    #[ignore]

lance-encoding/src/encodings/physical/fixed_size_binary.rs
283:    #[ignore] // This test is quite slow in debug mode

lance-encoding/src/encodings/physical/dictionary.rs
547:    #[ignore] // This test is quite slow in debug mode

lance-encoding/src/encodings/logical/list.rs
1900:    #[ignore] // This test is quite slow in debug mode

lance-encoding-datafusion/src/zone.rs
699:    #[ignore]

lance-index/src/scalar/bitmap.rs
448:    #[ignore]
((.venv) ) ➜  rust git:(3515-test-read-logic) ✗ ack "#\[ignore" | wc -l
      9

Start with the nine ignored tests listed in the issue, including lance-io/tests/gcs_integration.rs and the lance-encoding, lance-encoding-datafusion, and lance-index test files. Review the repository's existing build and CI configuration, then determine how to run these tests separately from the normal suite. Done means the slow or nightly build runs them automatically without making the regular build wait for them.