Intent of host_limit_emitted_when_frontend_service_count_is_not_set

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
  - service/ 1 test
    
    frontend/ 1 test
    
    TestNamespaceRateLimitMetrics/ 1 test
    
    go.temporal.io/server/service/frontend/TestNamespaceRateLimitMetrics/host_limit_emitted_when_frontend_service_count_is_not_set Introduced here