[Migration Tools] Research and implement a way to store integration tests passwords securely

[vmutafov]

For the migration tools E2E integration tests we need a way to store the Neo and HANA test users' passwords and emails. We should check if the other XSK modules have such scenarios and how they deal with them. If this problem exists in other modules as well, we should use some key vault to store the passwords without the need to hardcode them in the code.

[ThuF]

Shouldn't these credentials be provided via environment variables? There shouldn't be any hardcoded values in the integration tests.

[ThuF]

Environment variables will be used and for CI/CD purposes the credentials will be provided via GitHub Actions Credentials.