Optimize Egress sync process

[Jexf]

1. Ignore handling the Egress with empty Egress IP in Antrea Agent addEgress event.
2. Compare CR Generation in informer update event to ignore CR Status change.
3. Ignore handling the Egress IP Add event in onLocalIPUpdate process, which the IP already has been assigned by ipAssigner.

Fixes: #2880

Signed-off-by: Wu zhengdong zhengdong.wu@transwarp.io

[Jexf]

/test-all
/test-ipv6-only
/test-ipv6-all
/test-e2e

[codecov-commenter]

Codecov Report

Merging #2884 (5c8bab1) into main (95e836d) will decrease coverage by 8.93%.
The diff coverage is 24.00%.

@@            Coverage Diff             @@
##             main    #2884      +/-   ##
==========================================
- Coverage   61.18%   52.24%   -8.94%     
==========================================
  Files         284      283       -1     
  Lines       23494    23797     +303     
==========================================
- Hits        14374    12432    -1942     
- Misses       7565     9979    +2414     
+ Partials     1555     1386     -169     

Flag	Coverage Δ
kind-e2e-tests	31.41% <0.00%> (-17.25%)	⬇️
unit-tests	40.60% <24.00%> (-0.28%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/agent/controller/egress/egress_controller.go	38.32% <0.00%> (-1.47%)	⬇️
pkg/agent/memberlist/cluster.go	72.24% <100.00%> (+0.26%)	⬆️
pkg/controller/egress/controller.go	84.17% <100.00%> (+0.05%)	⬆️
pkg/controller/types/networkpolicy.go	0.00% <0.00%> (-100.00%)	⬇️
...g/agent/apiserver/handlers/featuregates/handler.go	0.00% <0.00%> (-82.36%)	⬇️
pkg/agent/controller/networkpolicy/packetin.go	4.50% <0.00%> (-67.50%)	⬇️
pkg/apis/controlplane/v1beta2/helper.go	33.33% <0.00%> (-66.67%)	⬇️
...formers/externalversions/security/v1alpha1/tier.go	0.00% <0.00%> (-64.29%)	⬇️
...ers/externalversions/core/v1alpha2/clustergroup.go	0.00% <0.00%> (-64.29%)	⬇️
...s/externalversions/core/v1alpha2/externalentity.go	0.00% <0.00%> (-64.29%)	⬇️
... and 110 more

[Jexf]

/test-e2e
/test-ipv6-e2e

[Jexf]

/test-all
/test-ipv6-only
/test-ipv6-all
/test-e2e
/test-ipv6-e2e

[Jexf]

@tnqn Can you help me review this PR again?

[Jexf]

/test-all
/test-ipv6-only
/test-ipv6-all

[tnqn]

LGTM