Add GxE flag to old studies for which is is missing.

[ljwh2]

All GxE interaction studies should have the GxE flag set to true (curators assign this by ticking a box in the curation app, or entering information in the submission metadata template).

A user reported that the flag is not set correctly for all old studies. A list of ~50 studies with missing flag is attached, it is too time consuming for curators to manually edit all of these so they should be edited directly in the database by a developer. https://app.zenhub.com/files/2995118/26bc6a44-9d34-4fd6-afe6-687538a3aa42/download

[ljwh2]

@ala-ebi this will also need doing before we release the data access features