Make the 'issuables list meta-data' shared example less dangerous

This shared example would take an object's database ID and create a number of objects based on it. If for some reason the ID were a high number, like 20, this would create 20 + 21 + 22 objects.

Not only was this dangerous from a performance perspective, it was entirely unnecessary, as the behavior it was testing is already well-tested in the unit test for the underlying object. For a controller test, which is what's including this shared example, all we need to do is verify that the assigned object contains the correct id => object Hash, which is what we now test for.