feat(pom.xml): parse `maven-metadata.xml` files for snapshot repositories.

[DmitriyLewen]

Description

We updated logic for repositories from pom files: #6171, #6412.

But some snapshot repositories (e.g. oss) use maven-metadata.xml file to get url of pom file. see more in https://github.com/aquasecurity/trivy/pull/6412#issuecomment-2058352431 We also need to add this logic.