add external redis username config to support redis6 ACL

[MinerYang]

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Comprehensive Summary of your change

Issue being fixed

#15895

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• Well Written Title and Summary of the PR
• Label the PR as needed. "release-note/ignore-for-release, release-note/new-feature, release-note/update, release-note/enhancement, release-note/community, release-note/breaking-change, release-note/docs, release-note/infra, release-note/deprecation"
• Accepted the DCO. Commits without the DCO will delay acceptance.
• Made sure tests are passing and test coverage is added if needed.
• Considered the docs impact and opened a new docs issue or PR with docs changes if needed in website repository.

[codecov]

Codecov Report

Merging #18364 (48a83b4) into main (321d8a0) will increase coverage by 26.16%.
The diff coverage is n/a.

❗ Current head 48a83b4 differs from pull request most recent head de38b4e. Consider uploading reports for the commit de38b4e to get more accurate results

@@             Coverage Diff             @@
##             main   #18364       +/-   ##
===========================================
+ Coverage   44.49%   70.66%   +26.16%     
===========================================
  Files         233      741      +508     
  Lines       13022    93388    +80366     
  Branches     2660        0     -2660     
===========================================
+ Hits         5794    65991    +60197     
- Misses       6933    23839    +16906     
- Partials      295     3558     +3263     

Flag	Coverage Δ
unittests	70.66% <ø> (+26.16%)	⬆️

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see 974 files with indirect coverage changes

[wy65701436]

lgtm

[chlins]

lgtm

[MinerYang]

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