feat: implement posterior prob filter for COLOC at small overlaps N<10

[xyg123]

✨ Context

There is instability of COLOC at small overlaps due to inflation of the likelihood term calculation, the problem is overviewed in the issue.

🛠 What does this PR implement

We now only pass small overlaps to COLOC if the overlapping probabilities are > 0.9 on both sides, which means the inflated H4s will be likely to be true colocalisation results. The parameters chosen here, PP > 0.9 and N <10 to achieve a comparable proportion of significant h4 results with the prev. OTG portal.

	Total Colocalisation Results	Number of COLOC H4 > 0.8	Percentage of COLOC H4 > 0.8
Gentropy release 24.12	23,709,155	17,553,867	74.04%
OTG portal release 22.10	7,408,493	4,357,079	58.81%
Gentropy 24.12 N>10	8,566,692	4,530,616	52.88%

Tests related to COLOC have been adjusted accordingly, to include posterior probabilities of >0.9 on both sides to prevent filtering out.

🙈 Missing

Future work will involve dynamic penalising of the prior term in H4 calculations, when the overlaps are small.
Implement parameters into COLOC method

🚦 Before submitting

• [ x] Do these changes cover one single feature (one change at a time)?
• [ x] Did you read the contributor guideline?
• [ x] Did you make sure to update the documentation with your changes?
• [ x] Did you make sure there is no commented out code in this PR?
• [ x] Did you follow conventional commits standards in PR title and commit messages?
• [ x] Did you make sure the branch is up-to-date with the dev branch?
• [ x] Did you write any new necessary tests?
• [ x] Did you make sure the changes pass local tests (make test)?
• [ x] Did you make sure the changes pass pre-commit rules (e.g poetry run pre-commit run --all-files)?

[xyg123]

@addramir Please let me know if you'd like to discuss changing the parameters (PP > 0.9 and N<10).