refactor endpoint slice packing strategy

[haouc]

What type of PR is this?

improvement
Which issue does this PR fix:

What does this PR do / Why do we need it:
Currently we pack endpoints of rules and pods to splitted slices based on configured chunk size. The issue is slices are packed eventually and unbounded growing when doing frequent resources scaling. We want to implement bin packing to ensure the slices are evenly packed and slice number growing expect-able and manage-able.

If an issue # is not available please add steps to reproduce and the controller logs:

Testing done on this change:

The change has been tested with rules and pods by scaling up/down. The slices were verified being filled evenly and bin packed.

For example:
chunk size is 5

% k scale deploy nginx --replicas=5                                                      
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length'      
5
% k scale deploy nginx --replicas=15                                                
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length' 
5
5
5
% k scale deploy nginx --replicas=17                                                
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length' 
5
5
2
5
% k scale deploy nginx --replicas=15                                                
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length' 
5
5
5
% k scale deploy nginx --replicas=11                                                
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length' 
1
5
5
% k scale deploy nginx --replicas=5                                                 
deployment.apps/nginx scaled
% k get policyendpoint -ojson | jq -r '.items[].spec.podSelectorEndpoints | length' 
5

Automation added to e2e:

Will this PR introduce any new dependencies?:

Will this break upgrades or downgrades. Has updating a running cluster been tested?:

Does this PR introduce any user-facing change?:

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[haouc]

Close this PR since we want to implement it different way.