bug: OpenAPM not masking the path in some cases

[chtushar]

Describe the bug

After instrumenting the express app. In some cases OpenAPM is not masking the paths using openapm.instrument('express') signature. The paths in the screenshot should be prefixed with /org/:orgId/

To Reproduce
Steps to reproduce the behavior:

1. Generate a demo express application using npx express-generator
2. Use openapm.instrument('express') as per the documentation
3. Create a router and use a parameter in the base path
4. Start the application and make calls to the paths initialized in the router.
5. localhost:9097/metrics won't have a parameterised routes.

Expected behavior
The paths should be parameterized like it is in the screenshot. When the middleware is used directly like this
app.use(openapm.REDMiddleware); the behaviour seems to be as expected.

[prathamesh-sonpatki]

@chtushar, Let's unify the signatures and add test coverage. Also share the example to repro this.