client: implement maxAttempts for retryPolicy

[imoore76]

Addresses #4615

RELEASE NOTES: none

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: imoore76 / name: Ian Moore (d6cf947)

[codecov]

Codecov Report

Attention: Patch coverage is 73.91304% with 6 lines in your changes are missing coverage. Please review.

Project coverage is 80.56%. Comparing base (adf976b) to head (cab3751).
Report is 51 commits behind head on master.

❗ Current head cab3751 differs from pull request most recent head d6cf947. Consider uploading reports for the commit d6cf947 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7223      +/-   ##
==========================================
- Coverage   81.24%   80.56%   -0.68%     
==========================================
  Files         345      349       +4     
  Lines       33941    34057     +116     
==========================================
- Hits        27574    27439     -135     
- Misses       5202     5427     +225     
- Partials     1165     1191      +26     

Files	Coverage Δ
dialoptions.go	89.38% <100.00%> (+0.22%)	⬆️
service_config.go	80.98% <ø> (+1.93%)	⬆️
clientconn.go	92.29% <66.66%> (+1.52%)	⬆️
stream.go	81.30% <25.00%> (-0.18%)	⬇️

... and 32 files with indirect coverage changes