disallow to configure traffic or match when a step has replicas more than threshold, for partition-style release only

[myname4423]

Ⅰ. Describe what this PR does

add check to webhook of creating and updating Rollout, if a partition-style release step has replicas configured more than threshold (defaults to 30%), this step mustn't be configured with traffic strategy (ie. traffic and matches must leave empty).
Note:

1. user can add an annotation rollouts.kruise.io/partition-replicas-limit to Rollout to configure the threshold, for example, user may set rollouts.kruise.io/partition-replicas-limit: 100% to virtually "disable" this check.
2. this restriction only works for partition-style release, both for v1alpha1 and v1beta1
3. this check is only for replicas in percentage format, since we cannot obtain the replicas from workload when doing this check (the workload might not have been submitted yet)
4. if users use weight field without specifying replicas (a common practice for v1alpha1, which is converted to replicas and traffic fields of v1beta1 with the same value automatically), they will encounter failure if weight is greater than the threshold.

edit: modified the e2e tests to obey this restriction

Ⅱ. Does this pull request fix one issue?

Ⅲ. Special notes for reviews

[codecov]

Codecov Report

Attention: Patch coverage is 46.87500% with 68 lines in your changes missing coverage. Please review.

Project coverage is 43.82%. Comparing base (07c1731) to head (9b819b3).
Report is 6 commits behind head on master.

Files	Patch %	Lines
pkg/controller/rollout/rollout_canary.go	5.26%	34 Missing and 2 partials ⚠️
pkg/trafficrouting/manager.go	44.82%	10 Missing and 6 partials ⚠️
...ollout/validating/rollout_create_update_handler.go	76.92%	4 Missing and 2 partials ⚠️
pkg/util/rollout_utils.go	0.00%	5 Missing ⚠️
...ok/rollout/validating/validate_v1alphal_rollout.go	83.33%	3 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #225      +/-   ##
==========================================
+ Coverage   43.63%   43.82%   +0.19%     
==========================================
  Files          52       53       +1     
  Lines        5681     6037     +356     
==========================================
+ Hits         2479     2646     +167     
- Misses       2778     2925     +147     
- Partials      424      466      +42     

Flag	Coverage Δ
unittests	43.82% <46.87%> (+0.19%)	⬆️

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[furykerry]

Instead of having users manually set the proportion, we aim to achieve this through the Service and/or the upper-level load balancing mechanism.

this sentence is confusing

[furykerry]

/lgtm

[zmberg]

/approve

[kruise-bot]

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