Remove Computed values from Pipeline where not required

[mcncl]

Problem

Setting a Default value of nil on the schema will inherit the nil value of its type; default_timeout_in_minutes, for example, will be set as 0 which will cause a command to never timeout (it's the same as setting no timeout).

Solution

Setting int values to a sensible default (the one shown in the docs) when values are not defined by the user.

Additional

We have a number of fields set as Computed which need not be; a computed value is one that the user will likely never interact with.