Outdated references to graph.properties

[optionsome]

While browsing through changes made in #2516 I noticed there are still references to graph.properties file, which as far as I know, can't be used anymore in the current version of OTP. I think those comments should be updated as they are confusing unless graph.properties file can somehow still be used.

Expected behavior

There should be no references to graph.properties anymore.

Observed behavior

There are comments that still refer to graph.properties file which is not being used anymore as it was split into router-config.json and builder-config.json

[t2gran]

This is fixed.