fix(db): check schema version for image name only

[DmitriyLewen]

Description

We add tag (schema version) to trivy-db and trivy-java-db repositories (#6219).
But url can contain : not in image name.
In this case we will not add tag.
See example in #6409.

So we need to check schema version for image name only.

Related issues

• Close Missing schema-version for download java-db in trivy 0.50.1 if repo url contains : #6409

Related PRs

• fix(db): use schema version as tag only for trivy-db and trivy-java-db registries by default #6219

Checklist

• I've read the guidelines for contributing to this repository.
• I've followed the conventions in the PR title.
• I've added tests that prove my fix is effective or that my feature works.
• I've updated the documentation with the relevant information (if needed).
• I've added usage information (if the PR introduces new options)
• I've included a "before" and "after" example to the description (if the PR is a user interface change).