Handle RefSeq transcript annotations in canonical transcripts pipeline

[nawatts]

VEP annotations for Ensembl transcripts do not include version numbers, whereas annotations for RefSeq transcripts do.

For RefSeq transcripts, the version number needs to be removed when collecting canonical transcripts to match how Ensembl transcripts are handled.

https://github.com/broadinstitute/gnomad-browser/blob/b4e38686e23fe4a31ff7c9541fe78b82b4df286b/data-pipeline/src/data_pipeline/data_types/canonical_transcript.py#L11