Experiment enrollment monitoring sample ratio mismatch p-value should be based on the number of branches

[scholtzan]

these cutoffs are dependent on the number of branches in the experiment. These are from a 2-branch experiment but for 3 (or more) branch experiments they give the wrong results 2-branch experiments should come from line 1 of the linked table, 3 branch from line 2, etc.

We can pull in the experimenter_experiments table to determine the number of branches.