mutated-genes/cna-genes endpoints return too much data when study has panels

[zhx828]

This is a new feature introduced in https://github.com/cBioPortal/cbioportal/pull/5994/files.

But when gene panel has long list of genes, the data can easily goes up to hundred megabytes. For instance in this cell line study, the panel has around 5000 genes. https://www.cbioportal.org/study/summary?id=cellline_ccle_broad

Proposed solution:
The matchingGenePanels does not return the full list of the genes and description but only the genePanelId, and also study view will fetch the gene panel info separately for further frequency calculation.