Update Bracken to accept separate Kraken2 build files to prevent symlink in symlink issues

[jfy133]

Same thing as here: #9163

Shuttling file symlinks (from filesystem outside work directory) inside directory symlinks (i.e., between processes), causes mounting issues with docker images.

This provides a way to remove the symlinking database directory between processes, and allowing docker or w/e to follow only file symlinks.

It's ugly, but it should work

PR checklist

Closes #XXX

• This comment contains a description of changes (with reason).
• If you've fixed a bug or added code that should be tested, add tests!
• If you've added a new tool - have you followed the module conventions in the contribution docs
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    • nf-core modules test <MODULE> --profile docker
    • nf-core modules test <MODULE> --profile singularity
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  • For subworkflows:
    • nf-core subworkflows test <SUBWORKFLOW> --profile docker
    • nf-core subworkflows test <SUBWORKFLOW> --profile singularity
    • nf-core subworkflows test <SUBWORKFLOW> --profile conda

[JoseEspinosa]

Because of the mv this process will be rerun each time a pipeline containing it will be resumed, as we just discussed, but as it seems that the issue can not be fixed in a different way, go ahead 😄