Make request paths configurable

[colmsnowplow]

Before this PR, data would be generated for paths at random - including randomly generated paths - the same behaviour is preserved, except the likelihood of random generation for each is now configurable, and one can also optionally add a custom path.

This solves a few problems:

• Randomly generated paths will create a lot of data that will fail at enrich - for e2e tests this might not be the desired effect
• Sometimes the random path generated constitutes a redirect path, which the collector correctly rejects
• If we do want to test redirect paths, without the custom path option we cannot do so
• We could now distribute load across specific endpoints should we need to