Resolve "Replace sync traversal_ids locking mechanism"

What does this MR do?

Replace traversal_ids lock mechanism.

1. Lock on root ancestor instead of the results of the CTE which does not work as expected. Discussion at !57318 (comment 543437858)
2. When moving a namespace to another hierarchy, lock the root ancestors of the original hierarchy and the new hierarchy. Discussion at !57318 (comment 553006573)

Lock on root ancestor

SELECT "namespaces".* FROM "namespaces" WHERE "namespaces"."type" = 'Group' AND "namespaces"."id" = 2 LIMIT 1 FOR UPDATE

Lock root ancestor of both the original and new hierarchy.

SELECT 
  "namespaces"."id" 
FROM 
  "namespaces" 
WHERE 
  "namespaces"."id" IN (
    SELECT 
      "namespaces"."id" 
    FROM 
      (
        SELECT 
          "namespaces".* 
        FROM 
          "namespaces" 
          INNER JOIN (
            SELECT 
              "id", 
              "depth" 
            FROM 
              (
                WITH RECURSIVE "base_and_ancestors" AS (
                  (
                    SELECT 
                      "namespaces".* 
                    FROM 
                      "namespaces" 
                    WHERE 
                      "namespaces"."id" IN (1, 3)
                  ) 
                  UNION 
                    (
                      SELECT 
                        "namespaces".* 
                      FROM 
                        "namespaces", 
                        "base_and_ancestors" 
                      WHERE 
                        "namespaces"."id" = "base_and_ancestors"."parent_id"
                    )
                ) 
                SELECT 
                  DISTINCT "namespaces".*, 
                  ROW_NUMBER() OVER () as depth 
                FROM 
                  "base_and_ancestors" AS "namespaces"
              ) AS "namespaces"
          ) namespaces_join_table on namespaces_join_table.id = namespaces.id 
        ORDER BY 
          "namespaces_join_table"."depth" ASC
      ) AS "namespaces" 
    WHERE 
      "namespaces"."parent_id" IS NULL
  ) 
ORDER BY 
  "namespaces"."id" ASC FOR 
UPDATE

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
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• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team

Related to #326785 (closed)