* fix: remove rimrafSync in importIndexedDir fast-path error handler
When parallel processes import the same package into the global virtual
store, a transient error in one process's fast path would trigger
rimrafSync on the shared directory, deleting files that other processes
already completed or are actively reading. The staging path that follows
already handles replacing the directory correctly via renameOverwriteSync.
* test: add test for fast-path failure not deleting populated GVS directory
Simulates a transient I/O error during the fast-path import while another
process has already populated the target directory. Verifies that the
directory is preserved and the staging path recovers correctly.
Zoltan Kochan
4ba4bf33c8