Remove redundant cache lookup debug logging. (#12395)
Remove redundant cache lookup debug logging. (#12395)

The cache lookup workunit (a few lines up) already mutates itself to report the hit, so additionally reporting the hit on the parent workunit is redundant, and looks like:
```
15:30:10.02 [DEBUG] Completed: Hit: Local cache lookup: Determine Python imports for src/python/pants/engine/internals/mapper_test.py:tests
15:30:10.03 [DEBUG] Completed: Hit local cache: Scheduling: Determine Python imports for src/python/pants/engine/internals/mapper_test.py:tests
```
pantsbuild/pants,pantsbuild/pants,pantsbuild/pants,benjyw/pants,pantsbuild/pants,pantsbuild/pants,pantsbuild/pants,benjyw/pants,benjyw/pants,benjyw/pants,benjyw/pants,benjyw/pants,benjyw/pants,pantsbuild/pants