little changes to the fall back logic + tests

[xTRam1]

Instead of storing the vcpu limits as a hardcoded variable inside Planner, created a new .csv file that includes that information. When Planner is created, we read this csv file.

Wrote test cases that include fake quota limits.

[sarahwooders]

Could you also add a warning for when the VMs are falling back to smaller instance types? e.g. logger.fs.warning(f"Falling back to instance type {instance_name} due to VCPU limit of {vcpu_limit} in region {region}")

[xTRam1]

I have a warning at planner.py L304, would you like me to change the warning message?