parallel/sequence v1beta reconcilers

[vaikas]

Fixes #

Proposed Changes

• Use v1beta1 api to reconcile parallel/sequence
• Run sequence e2e tests with all the channel types. Previously was only using IMC v1beta1.
• Run parallel e2e tests with all the channel types. Previously was only using IMC v1beta1.

Release Note

- 🧽 Update or clean up current behavior

Docs

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: vaikas

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• OWNERS [vaikas]

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[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-knative-eventing-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/apis/flows/v1beta1/sequence_lifecycle.go	2.3%	95.3%	93.0
pkg/reconciler/parallel/parallel.go	69.2%	69.4%	0.2
pkg/reconciler/sequence/sequence.go	70.6%	71.9%	1.3

[lionelvillard]

works for me.

/lgtm