Intent of does_nothing_for_unset_key

All 1 exact test in this concept. Every test is marked by where it enters the hierarchy.

go.temporal.io/ 1 test
- server/ 1 test
  - common/ 1 test
    
    testing/ 1 test
    
    testhooks/ 1 test
    
    TestCall/ 1 test
    
    go.temporal.io/server/common/testing/testhooks/TestCall/does_nothing_for_unset_key Introduced here