We should convert https://github.com/10gen/mongo/blob/master/evergreen/functions/code_coverage_data_process.sh to a Python script to ease maintenance.

Draft PR that is nearly complete: https://github.com/10gen/mongo/pull/27906

PB that still has some warts: https://spruce.mongodb.com/version/67052e2bb40ff200074b91e0/tasks?sorts=STATUS%3AASC%3BBASE_STATUS%3ADESC
For some reason it is not finding coverage files (gcno/gcda) where they are known to be from the shell-version of the script. I'm guessing current directories changed subtly.