Re-think delivery of runs/metadata.json and runs/validation_errors.json.

[bpblanken]

Currently delivered as a file, to either a local or remote HAIL_SEARCH_DATA_DIR. This isn't ideal because the seqr pod shouldn't have access to that directory.

[bpblanken]

Also of note:

we've run into race conditions with the current setup, the cron can run and add loaded samples to seqr before the on-disk copies are available.