router check tool: support coverage for routes with runtime set to 100%

The router check tool tests for runtime by treating the runtime setting as enabled when the `random_value` field is less than the fractional percentage set in the default fraction for the runtime field. To account for when the numerator was 0 (i.e. runtime disabled by default), the tool treats the route as though the numerator is 1 so that users can test for coverage.

A similar workaround needs to be implemented for runtime fractions of 100% (i.e. when the route has runtime enabled by default).