Unset default limit of 20 samples when gathering metadata for grapetree data

[alkc]

Closes #39

This tiny fix ensures that metadata is returned for all queried samples when gathering metadata clustering, instead of just the 20 first samples.

How to setup and perform the tests

1. Setup bonsai instance and add N > 20 samples to the database
2. Login, add N > 20 samples to the basket
3. Open basket and select Cluster
4. In the grapetree view, right click the tree and select show metadata table
5. Confirm that metadata is displayed for all samples and not just the 20 first

Expected outcome

The table should be populated with metadata for all samples, not just the first 20 samples.