Add support for istio LEAST_REQUEST destination rule load balancing

[Codasquieves]

Istio will deprecate LEAST_CONN option of destination rule load balancing algorithms and LEAST_REQUEST type is being used instead of LEAST_CONN.

istio code

[stefanprodan]

Please run make codegen and make fmt.

[stefanprodan]

LGTM

Thanks @Codasquieves please squash the two commits and force push.

[aryan9600]

sorry to leave this unattended, @Codasquieves could you please rebase against main? we'll be ready to merge then :)

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.02 🎉

Comparison is base (2b80c47) 54.52% compared to head (18e6afa) 54.54%.

❗ Current head 18e6afa differs from pull request most recent head 7d29af4. Consider uploading reports for the commit 7d29af4 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1439      +/-   ##
==========================================
+ Coverage   54.52%   54.54%   +0.02%     
==========================================
  Files          84       84              
  Lines       10142    10140       -2     
==========================================
+ Hits         5530     5531       +1     
+ Misses       3955     3953       -2     
+ Partials      657      656       -1     

see 1 file with indirect coverage changes

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[aryan9600]

@Codasquieves we prefer rebases over merge :)

[aryan9600]

lgtm, thanks @Codasquieves 🎖️