feat: Enable the configuration of topologySpreadConstraints for the EG control plane.

[alexwo]

What this PR does / why we need it:
Given that Envoy Proxy is deployed with leader election enabled by default, it makes sense to provide an easy option to allow it to run across multiple availability zones to achieve a high availability (HA) deployment. One option currently available to achieve this is using pod affinity; however, adding topologySpreadConstraints offers even greater flexibility.

deployment:
 pod:
  topologySpreadConstraints:
   - topologyKey: kubernetes.io/hostname
     maxSkew: 1
     whenUnsatisfiable: DoNotSchedule
     labelSelector:
       matchLabels:
         app: envoyproxy
         control-plane: envoy-control-plane
   - topologyKey: topology.kubernetes.io/zone
     maxSkew: 1
     whenUnsatisfiable: ScheduleAnyway
     labelSelector:
       matchLabels:
         app: envoyproxy

Fixes #
#3534

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 68.15%. Comparing base (3712659) to head (343ea55).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3535      +/-   ##
==========================================
+ Coverage   68.12%   68.15%   +0.03%     
==========================================
  Files         165      165              
  Lines       20122    20122              
==========================================
+ Hits        13708    13715       +7     
+ Misses       5416     5411       -5     
+ Partials      998      996       -2     

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[alexwo]

/retest

[guydc]

LGTM

[cnvergence]

👍🏻

[arkodg]

/retest

to kick DCO

[arkodg]

DCO is broken in the server side, more in dcoapp/app#211
temporarily disabled it for now, until this issue is resolved