Rename functions "util.Remove" (remove.go) to "util.RemoveWithRetry"
(file_retry.go) and add comments to clarify their behaviors, also add
tests.
Refactor callers: when no concurrent access (cmd cli, migration, app
init, test), use "os.Xxx" directly.
More details are in `modules/util/file_retry.go`
By the way, clean up OS (windows) detection, make FileURLToPath test
always run