Allow BoardListType.issues to filter by negated issueType in GraphQL

What does this MR do and why?

BoardListType.issues filter would allow a negated issueType input argument, but if provided, it would have no effect on the IssueFinder.

Database plans

For negated issue_type filtering

https://console.postgres.ai/shared/ebf9b43c-69b1-46cb-9c6e-9c67cdee738f

RAW SQL

SELECT "issues".*
FROM   "issues"
WHERE  "issues"."id" IN (SELECT "issues"."id"
                         FROM   "issues"
                                LEFT JOIN banned_users
                                       ON banned_users.user_id =
                                          issues.author_id
                         WHERE  banned_users.user_id IS NULL)
       AND "issues"."project_id" = 278964
       AND ( "issues"."state_id" IN ( 1 ) )
       AND "issues"."issue_type" != 0 

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MR acceptance checklist

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Related to #328240 (closed) and #337662 (closed)