Why I did it
Optimize the version control for Debian packages.
Fix sonic-slave-buster/sources.list.amd64 not found display issue, need to generate the file before running the shell command to evaluate the sonic image tag.
When using the snapshot mirror, it is not necessary to update the version file based on the base image. It will reduce the version dependency issue, when an image is not run when freezing the version.
How I did it
Not to update the version file when snapshot mirror enabled.
How to verify it
Why I did it
Unify the Debian mirror sources
Make easy to upgrade to the next Debian release, not source url code change required. Support to customize the Debian mirror sources during the build
Relative issue: #12523
How I did it
How to verify it
