fix: updating info in finngen study index ingestion

[Daniel-Considine]

✨ Context

FinnGen R12 has 500,348 participants (282,064 females and 218,284 males). This PR updates the initialSampleSize column in the StudyIndex.

🛠 What does this PR implement

🙈 Missing

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[project-defiant]

@Daniel-Considine Approved, but reflecting at this, having this stat hardcoded is not so good, since it always references r12 release.

[Daniel-Considine]

@Daniel-Considine Approved, but reflecting at this, having this stat hardcoded is not so good, since it always references r12 release.

@project-defiant I agree, but R12 is meant to be the last FinnGen release, so it shouldn't be a problem in the future.