Hidden Sample Types should not be used as filters

[kdp-cloud]

Describe the bug When the user goes to /samples, he / she can filter the samples on 'hidden' sample types that were created in Single Page, which is not consistent since the user never deals directly with sample types. It would be more appropriate to replace those 'hidden' sample type filters with filters of the studies and assays, those sample types are linked to.

Screenshot

[floradanna]

Although hidden ST can be used to filter, DataHub users are not able to see the ST and therefore, they cannot create samples via default view. This makes the issue less urgent to solve.