Allow re-dismissing vulnerabilities

What does this MR do and why?

This change allows re-dismissing vulnerabilities that have already been dismissed. It reverts a recommended change as per UX guidance.

explain SELECT
  "vulnerabilities"."id",
  "vulnerabilities"."state",
  "vulnerabilities"."project_id"
FROM
  "vulnerabilities"
WHERE
  "vulnerabilities"."id" IN (4326, 4327, 4328, 4329, 4330, 4331, 4332, 4333, 4334, 4335, 4336, 4337, 4338, 4339, 4340, 4341, 4342, 4343, 4344, 4345, 4346, 4347, 4348, 4349, 4350, 4351, 4352, 4353, 4354, 4355, 4356, 4357, 4358, 4359, 4360, 4361, 4362, 4363, 4364, 4365, 4366, 4367, 4368, 4369, 4370, 4371, 4372, 4373, 4374, 4375, 4376, 4377, 4378, 4379, 4380, 4381, 4382, 4383, 4384, 4385, 4386, 4387, 4388, 4389, 4390, 4391, 4392, 4393, 4394, 4395, 4396, 4397, 4398, 4399, 4400, 4401, 4402, 4403, 4404, 4405, 4406, 4407, 4408, 4409, 4410, 4411, 4412, 4413, 4414, 4415, 4416, 4417, 4418, 4419, 4420, 4421, 4422, 4423, 4424, 4425);

https://console.postgres.ai/gitlab/gitlab-production-tunnel-pg12/sessions/21017/commands/68719

#418825 (closed)

How to set up and validate locally

1. Visit the graphql explorer http://gdk.test:3000/-/graphql-explorer
2. Execute the mutation

   mutation dismissVulnerabilities($ids: [VulnerabilityID!]!, $comment: String!) {
     vulnerabilitiesDismiss(
       input: {vulnerabilityIds: $ids, comment: $comment, dismissalReason: USED_IN_TESTS}
     ) {
       vulnerabilities {
         id
         state
         dismissedAt
         dismissedBy {
           name
         }
         stateTransitions {
           nodes {
             dismissalReason
             fromState
             toState
             comment
             author {
               name
             }
           }
         }
       }
       errors
     }
   }

   {
     "ids": [
       "gid://gitlab/Vulnerability/100",
       "gid://gitlab/Vulnerability/101",
       "gid://gitlab/Vulnerability/102"
     ],
     "comment": "A comment"
   }

3. Verify the results by checking that the state is DISMISSED and that the stateTransitions includes a transition with a toState of DISMISSED.
4. Re-run the same mutation with a different dismissal reason.
5. Verify that the new dismissal reason is returned in the results.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

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