* chore: streamline GH actions
* force use of local piper
* look for piper in project root
* use local piper
* Update .github/workflows/verify-go.yml
* remove chmod
This change allows a development workflow where you don't need to set the `PIPER_INTEGRATION_EXECUTABLE` variable if your executable is available in the CWD. This should make it non-required to set the variable for most cases of local development.
