Load correct iteration on iteration report

What does this MR do?

Found while unquarantining spec for #222915 (closed)

The following test previously failed (so one was quarantined:

bin/spring rspec ./ee/spec/features/issues/issue_sidebar_spec.rb ./ee/spec/features/groups/iterations/user_views_iteration_spec.rb

Database queries

Query:

SELECT "sprints".*
FROM (
        (SELECT "sprints".*
         FROM "sprints"
         WHERE "sprints"."iid" = 1
           AND 1=0)
      UNION ALL
        (SELECT "sprints".*
         FROM "sprints"
         WHERE "sprints"."iid" = 1
           AND "sprints"."group_id" = 9970)) sprints
WHERE "sprints"."iid" = 1
ORDER BY due_date ASC NULLS LAST,
                      "sprints"."title" ASC
LIMIT 100

Execution plan:

Limit  (cost=3.17..3.17 rows=1 width=186) (actual time=0.214..0.214 rows=0 loops=1)
   Buffers: shared hit=9 read=1
   I/O Timings: read=0.106
   ->  Sort  (cost=3.17..3.17 rows=1 width=186) (actual time=0.213..0.214 rows=0 loops=1)
         Sort Key: sprints.due_date, sprints.title
         Sort Method: quicksort  Memory: 25kB
         Buffers: shared hit=9 read=1
         I/O Timings: read=0.106
         ->  Append  (cost=0.12..3.16 rows=1 width=186) (actual time=0.126..0.126 rows=0 loops=1)
               Buffers: shared hit=3 read=1
               I/O Timings: read=0.106
               ->  Index Scan using index_sprints_on_group_id_and_title on public.sprints  (cost=0.12..3.15 rows=1 width=186) (actual time=0.124..0.124 rows=0 loops=1)
                     Index Cond: (sprints.group_id = 9970)
                     Filter: (sprints.iid = 1)
                     Rows Removed by Filter: 0
                     Buffers: shared hit=3 read=1
                     I/O Timings: read=0.106

Timings:

Time: 0.568 ms
  - planning: 0.303 ms
  - execution: 0.265 ms
    - I/O read: 0.106 ms
    - I/O write: 0.000 ms

Shared buffers:
  - hits: 9 (~72.00 KiB) from the buffer pool
  - reads: 1 (~8.00 KiB) from the OS file cache, including disk I/O
  - dirtied: 0
  - writes: 0