feat: Suppress envoy headers

[liorokman]

What this PR does / why we need it:

This PR implements #2358

Which issue(s) this PR fixes:
Implements #2358

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bda0055) 64.73% compared to head (2e4c8a5) 64.78%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2364      +/-   ##
==========================================
+ Coverage   64.73%   64.78%   +0.04%     
==========================================
  Files         113      113              
  Lines       16567    16575       +8     
==========================================
+ Hits        10725    10738      +13     
+ Misses       5168     5164       -4     
+ Partials      674      673       -1     

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[shawnh2]

lgtm

[arkodg]

we may need to revisit where this field lives in the future and consider moving it into BackendTrafficPolicy if

• this feature is something that is tied to the developer persona instead of the system admin persona
• if there are valid use cases where a user would like to enable this feature at the Gateway level (all HTTPRoutes ) by default but disable it for some explicit routes (using a explicit BackendTrafficPolicy targeted at the route level)