Unify ClusterAutoscaler configs

[liangxia]

ClusterAutoscaler is enabled on all of managed build farm clusters, unify the configs from configs inside each of the build farm cluster folder to one config file inside common.

$ for x in app.ci core-ci hosted-mgmt build{01..11} ; do echo "===$x:" ; oc --context $x get clusterautoscaler | grep default ; echo ; done
===app.ci:
default   4y312d

===core-ci:
default   91d

===hosted-mgmt:
default   689d

===build01:
default   6y36d

===build02:
default   272d

===build03:
default   311d

===build04:
default   272d

===build05:
default   100d

===build06:
default   470d

===build07:
default   381d

===build08:
default   164d

===build09:
default   291d

===build10:
default   337d

===build11:
default   412d

Also introduce a new option balanceSimilarNodeGroups: true to let Cluster Autoscaler to provision worker nodes evenly across Availability Zones.

[openshift-ci-robot]

[REHEARSALNOTIFIER]
@liangxia: no rehearsable tests are affected by this change

Note: If this PR includes changes to step registry files (ci-operator/step-registry/) and you expected jobs to be found, try rebasing your PR onto the base branch. This helps pj-rehearse accurately detect changes when the base branch has moved forward.

[liangxia]

/hold
Plan to get this in on next Monday.

[openshift-ci]

@liangxia: all tests passed!

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[bear-redhat]

/lgtm

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: bear-redhat, liangxia

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