Export GWAS data to Covid Portal should be during data release deployment

[sprintell]

GWAS EBI Search index export file (/nfs/production/parkinso/spot/gwas/prod/data/gwas-ebi-search-index-data/studies.json) is generated during the data release build stage, but this should be exported during the data release deployment stage as this file should not be available for external access until the data release is deployed

https://github.com/EBISPOT/gwas-ebi-search-index