Add s4s regions to reserved org slugs (#97316)

Validated all of these slugs are available by querying control silo and
got no results:

```
SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s'

SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s1'

SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s2'

SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s3'

SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s4'

SELECT * FROM sentry_organizationslugreservation WHERE slug = 's4s5'
```

Author: mwarkentin

src/sentry/constants.py

@@ -181,6 +181,12 @@ def get_all_languages() -> list[str]:
         "remote",
         "resources",
         "rollback",
+        "s4s",
+        "s4s1",
+        "s4s2",
+        "s4s3",
+        "s4s4",
+        "s4s5",
         "sa1",
         "sales",
         "security",