Add @type_check_only to stub-only private classes in stdlib
#13146
| Job | Run time |
|---|---|
| 47s | |
| 41s | |
| 40s | |
| 38s | |
| 43s | |
| 1m 39s | |
| 1m 27s | |
| 1m 12s | |
| 42s | |
| 49s | |
| 40s | |
| 1m 25s | |
| 29s | |
| 1m 15s | |
| 27s | |
| 45s | |
| 1m 10s | |
| 26s | |
| 15m 55s |