bug: benchmark.yml fails when tests/benchmarks/ doesn't exist in downstream projects

[endavis]

Bug Description

The benchmark.yml workflow hardcodes tests/benchmarks/ as the pytest path. When a downstream project syncs this workflow but doesn't have benchmark tests yet, the workflow fails with:

ERROR: file or directory not found: tests/benchmarks/

Steps to Reproduce

1. Sync benchmark.yml from the template to a downstream project
2. The downstream project does not have tests/benchmarks/
3. Push to trigger the benchmark workflow
4. Workflow fails with exit code 4

Expected vs Actual Behavior

Expected: Workflow succeeds gracefully when no benchmark tests exist
Actual: Workflow fails with file not found error

Proposed Fix

Check if the directory exists before running pytest. See endavis/pynetappfoundry#459 for the fix applied downstream.