Add sqlite timeout to obsdb

[mmccrackan]

Copies #1496 and adds the ability to specify the timeout for the obsdb sqlite connection through the same environment variable. This may help alleviate the locked obsdb failures we are having for the update_obsdb Prefect flow.

[mhasself]

Thanks.

This envvar is now used 3 times in code, but does not appear in any docs or docstrings. I think doesn't need to be your job but we should #1682