fix(generator): do not override default sleeper in streaming-read RPCs

[devbww]

This change is 

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (2c26eb9) 0.00% compared to head (b012b0d) 93.61%.

Additional details and impacted files

@@            Coverage Diff            @@
##           main   #12920       +/-   ##
=========================================
+ Coverage      0   93.61%   +93.61%     
=========================================
  Files         0     2067     +2067     
  Lines         0   180119   +180119     
=========================================
+ Hits          0   168627   +168627     
- Misses        0    11492    +11492     

Files	Coverage Δ
...v1/internal/golden_kitchen_sink_connection_impl.cc	77.35% <100.00%> (ø)
generator/internal/connection_impl_generator.cc	49.00% <ø> (ø)

... and 2065 files with indirect coverage changes

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