Excessive spacing in the select-data modal's tree hierarchy

[Xarthisius]

Bug found during testing of #78. Not a blocker, I'm just noting it so I won't forget.

Steps to Reproduce

1. Deploy fix: various fixes for the Run > Files view #78 and register Ligo Tale
2. Create a Tale
3. Navigate View Tale > Files > External Data
4. Click (+) / WT Data Catalog
5. In the Select from WT External Data Catalog select WT Catalog from the outer left panel, then in the inner left panel double-click on www.gw-openscience.org

Expected Results
Nicely formated tree showing folder named s

Actual Results

NOTES
Tested both on Chrome and Firefox. Looks the same.

[bodom0015]

Interesting... I believe this is related to whole-tale/girder_wholetale#304 (though I don't understand how), because I am also seeing this behavior on each of the resources with URLs.

Still looking into where the extra space is coming from