downgrade a log notice at startup

This was the only log notice that happened during other
tor invocations, like --verify-config and --list-fingerprint.
Plus, now we think it works, so no need to hear about it.

src/or/dirserv.c

@@ -2390,9 +2390,9 @@ dirserv_read_measured_bandwidths(const char *from_file,
   }
 
   fclose(fp);
-  log_notice(LD_DIRSERV,
-             "Bandwidth measurement file successfully read. "
-             "Applied %d measurements.", applied_lines);
+  log_info(LD_DIRSERV,
+           "Bandwidth measurement file successfully read. "
+           "Applied %d measurements.", applied_lines);
   return 0;
 }