Update lint checks for `modules_testdata_base_path` and `pipelines_testdata_base_path`

Description of feature

The parameters modules_testdata_base_path and pipelines_testdata_base_path currently need to be defined in both tests/nextflow.config and nextflow.config. To prevent duplication of parameter definitions, simplify updates, and reduce ambiguity, it would be better if parameters were only defined once. This should be done in nextflow.config only so that configs included here can access these variables, but it is currently not possible due to current linting checks, for example:

nf_test_content: 'tests/nextflow.config' does not contain pipelines_testdata_base_path

For this, it is necessary to:

• Remove modules_testdata_base_path and pipelines_testdata_base_path from tests/nextflow.config.
• Remove associated linting checks for the content of tests/nextflow.config.
• Add linting checks for the content of nextflow.config instead.

Inspect tests/nextflow.config and nextflow.config, then locate the lint checks that validate their parameter contents. Remove the duplicated parameters and update the checks so nextflow.config is validated instead; done when the lint checks pass with definitions only in nextflow.config.