test(NODE-6358): handle directories in bson versions

[durran]

Description

Fixes benchmark test names when the bson version points at a directory, eg bson:/path/to/bson.

What is changing?

Updates regex to strip from ":"

Is there new documentation needed for these changes?

None

What is the motivation for this change?

NODE-6358

Double check the following

• Ran npm run check:eslint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[durran]

Test failures unrelated, pass locally.

[nbbeeken]

Can we address the failing test? (Can skip)

[durran]

Skipped test and added todo.