Template: remove try-catch blocks from nextflow.config

[mirpedrol]

Close #3132

[mirpedrol]

One problem with this syntax is that the first time a user creates a pipeline, this will fail as nf-core/configs does not contain the pipeline config.
It can be solved by providing a false params.custom_config_base but it's not ideal. I would consider commenting out these lines on the template again and let users decide if they want to include a pipeline specific config.