Links that are redirects result in null topic QIDs.
For instance, on frwiki:
```
|revision_id| page_qid| page_title|section_id|section_title|topic_qid| topic_title|
+-----------+---------+---------------------------+----------+-------------+---------+-------------------------------------+
| 191906273| Q220408| Thomas François Burgers| 0| ### zero ###| null|République sud-africaine du Transvaal|
```
We should resolve the redirect into `République_sud-africaine_(Transvaal)` to enable the topic QID lookup.
See also https://gitlab.wikimedia.org/repos/structured-data/section-topics/-/merge_requests/1#note_10669
==Outcome==
The initial assessment was for the August 2022 snapshot, no relevance score, no excluded sections, no redirects:
- total rows = 1.83 B
- null topic titles = 42 M (~2.3%)
- null topic QIDs = **631 M**
- ratio **> 1/3**
Here we compare the impact of handling redirects for the `2022-11-07` snapshot, no relevance score, sections excluded as per ticked items in {T318092}:
- no redirects
- total rows = 1.74 B (1,743,028,345)
- null topic QIDs = **538 M** (537,750,071)
- ratio = **0.31**
- handled redirects
- total rows = 1.74 B (1,743,227,622)
- null topic QIDs = **384 M** (383,664,157)
- ratio = **0.22**
- **+9%** gain
The full pipeline for `2022-11-07`, i.e., with relevance score, sections excluded, no null topic QIDs yielded the following counts:
- no redirects = 1.2 B rows
- handled redirects = 1.36 B rows
- **+16 M** rows gain