Update audit event to include policies when CI allowlist is deleted

What does this MR do and why?

• Follows from !167872 (merged)
• Updates the existing allowlist add/remove audit events to store which job token permissions were attached to the allowlist entry.
• Also adds missing unit tests, per #498831

MR acceptance checklist

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Screenshots or screen recordings

How to set up and validate locally

1. Ensure that you are on an Ultimate subscription, and enable feature-flag in rails console:

Feature.enable(:add_policies_to_ci_job_token)

2. Navigate to GraphQL explorer, /-/graphql-explorer
3. Create an allowlist with a project as the target, using the following query:

mutation {
  ciJobTokenScopeAddGroupOrProject(input: {
    projectPath: "flightjs/Flight",
    targetPath: "gitlab-org/gitlab-test",
    jobTokenPolicies: [READ_PROJECT, READ_PACKAGE]
  }) {
    errors
  }
}

4. As an admin, navigate to audit events /admin/audit_logs
5. Repeat steps 3 and 4 to check the audit events are created when creating an allowlist with a group as the target, and deleting both the allowlists.

mutation {
  ciJobTokenScopeAddGroupOrProject(input: {
    projectPath: "flightjs/Flight",
    targetPath: "gitlab-org",
    jobTokenPolicies: [READ_GROUP, READ_PROJECT]
  }) {
    errors
  }
}

mutation {
  ciJobTokenScopeRemoveProject(input: {
    projectPath: "flightjs/Flight",
    targetProjectPath: "gitlab-org/gitlab-test",
    direction: INBOUND
  }) {
    errors
  }
}

mutation {
  ciJobTokenScopeRemoveGroup(input: {
    projectPath: "flightjs/Flight",
    targetGroupPath: "gitlab-org"
  }) {
    errors
  }
}

Related to #495144