[FEATURE] [Custom Map] Enable avoid having ids in a layer

[zstadler]

Is your feature request related to a problem? Please describe.
In layers that go though though merge_line_strings or merge_polygons post-processing, having ids in the vector tiles is often useless.
The capability to avoid having MVT ids for features in a particular layer is not currently exposed in the YAML configuration file .

Describe the solution you'd like
Any syntax that would prevent ids to be added to the layer will be welcome.

Describe alternatives you've considered
One of my failed attempts was:

    attributes:
    - key: id
      exclude_when: "true"

😄