Remove unneeded fields from ci_job_inputs

Problem

After the announcement of the new job descriptions table, we won't be storing any information about the job inputs spec in ci_job_inputs.

Solution

Remove all fields related to the spec from ci_job_inputs. Those fields are:

• sensitive
• input_type

This table is not currently in use, so we should be able to remove these fields without ignoring them first.

UPDATE:

18.5 -> ignoring columns

18.7 -> removing columns