testrunner: fold PreprocessorHelper into TestPreprocessor (#7848)
#19334
| Job | Run time |
|---|---|
| 12s | |
| 31s | |
| 23s | |
| 23s | |
| 1m 19s | |
| 1m 13s | |
| 1m 19s | |
| 1m 31s | |
| 1m 14s | |
| 1m 14s | |
| 1m 9s | |
| 1m 15s | |
| 11m 43s |