Stop using issue_type enum generated methods in issues

What does this MR do and why?

We are removing the issues.issue_type column, in favor of the new issue.work_item_type.base_type. Before we can do that, we need to remove every usage of the column from the codebase. This MR also introduces a new method for every issue_type in the enum column. The method will raise an error if anyone tries to use this column again through these methods. This will all be removed once the column is gone.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #410226 (closed)