Remove employee.expected_project_allocation

[jduss4]

The UserData model has a field, expected_project_allocation which appears to be unused. While the production data has values, they are mostly "1" and occasionally are somewhat inconsistent, with values like .6 and .5, and users with a 0 billable expectation still assigned a "1" expected allocation.

As we already have a field for expected_billable_hours from which one can derive an expected allocation, I recommend that this field is removed. However, it is not currently hurting anything where it is, either. I'm opening this issue as a space for discussion!

https://github.com/18F/tock/blob/main/tock/employees/models.py#L87

[MelissaBraxton]

Weighing in from the TLC Crew:

We think this is a good idea but it doesn’t currently fit with our near- or mid-term roadmap. This means we will not work on this in the next 3 months. We will revisit this in 3 months and check in then. In the meantime, if you find another way to get this work done feel free to choose that path. If you do find a different path to getting the work done and no longer want TLC crew help, please remove the issue from our project board.