Fixed regression in Router test

[stevieraykatz]

Closes all failing CI issues with:

/usr/local/bin/yarn tsc
Error: test/core/router/Router.ts(458,13): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: test/core/router/Router.ts(478,13): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: test/core/router/Router.ts(498,13): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: test/core/router/Router.ts(540,13): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: test/core/router/Router.ts(560,13): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: test/core/router/Router.ts(820,9): error TS2345: Argument of type 'Promise<string>' is not assignable to parameter of type 'string'.
Error: The process '/usr/local/bin/yarn' failed with exit code 2

Explanation of the solution

looks like some old lines of the Router test snuck in upon merge? either way, no need to query a mock contract for symbol. can specify directly to save runtime.

Instructions on making this work

• run yarn or yarn install to install npm dependencies