[PackageToJS] Fix flaky timestampBasedRebuild test by abstracting file system operations
#1763
| Job | Run time |
|---|---|
| 32s | |
| 38s | |
| 5m 40s | |
| 5m 17s | |
| 11m 10s | |
| 4m 43s | |
| 5m 16s | |
| 5m 48s | |
| 0s | |
| 39m 4s |