Adjust R length of warm-up to use intervals

[amyheather]

As discussed in pythonhealthdatascience/pydesrap_mms#85.

[amyheather]

Some other relevant notes from DES RAP Book:

parallel.qmd: On this page, we are making changes to the simulation code from the Replications page - but the Parameters class has been updated based on the determined length of warm-up, a data collection period of 2 weeks (20,160 minutes), and the determined number of replications.

length_warmup.qmd: | What to look for? | This model also uses an audit approach, but this is currently a method within Model itself, and only runs on a few performance measures (but this will be updated, as above, to use WarmupAuditor). |

length_warmup.qmd: | What to look for? | Uses time series inspection approach as above, but currently just uses a few performance measures (but this will be updated to include more). |