roachtest: mixedversion: sanitize both log path and prefix

Avoiding filenames with spaces on them is generally a good idea.

Epic: none

Release note: None

pkg/cmd/roachtest/roachtestutil/mixedversion/mixedversion.go

@@ -1064,16 +1064,15 @@ func newSingleStep(context *Context, impl singleStepProtocol, rng *rand.Rand) *s
 // prefixedLogger returns a logger instance off of the given `l`
 // parameter. The path and prefix are the same.
 func prefixedLogger(l *logger.Logger, prefix string) (*logger.Logger, error) {
-	filename := sanitizePath(prefix)
-	return prefixedLoggerWithFilename(l, filename, filename)
+	return prefixedLoggerWithFilename(l, prefix, prefix)
 }
 
 // prefixedLoggerWithFilename returns a logger instance with the given
 // prefix. The logger will write to a file on the given `path`,
 // relative to the logger `l`'s location.
 func prefixedLoggerWithFilename(l *logger.Logger, prefix, path string) (*logger.Logger, error) {
-	formattedPrefix := fmt.Sprintf("[%s] ", prefix)
-	return l.ChildLogger(path, logger.LogPrefix(formattedPrefix))
+	formattedPrefix := fmt.Sprintf("[%s] ", sanitizePath(prefix))
+	return l.ChildLogger(sanitizePath(path), logger.LogPrefix(formattedPrefix))
 }
 
 func sanitizePath(s string) string {