Remove need for realpath in analyzer-debug script

While helping a community contributor, I pointed them to the analyzer-debug script and they mentioned:

I had to install coreutils with Brew to get realpath so that step is sorted

I figure we should either:

1. Document the need to install coreutils in the README
2. Add a check to the analyzer-debug script to ensure that coreutils is installed
3. Remove the need for coreutils and use a bash-only solution

This MR implements option 3. from the above list.