Add CE Client to dynamic injection

[mattmoor]

I noticed log statements experimenting with using the dynamic injection logic with Tekton. Since it seems like the CE stuff is just piggybacking on injection (and not actually using the rest.Config) this should be a pretty trivial/benign change.

/kind cleanup

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• Docs included if any changes are user facing
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/assign @afrittoli

[tekton-robot]

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

File	Old Coverage	New Coverage	Delta
pkg/reconciler/events/cloudevent/cloudeventclient.go	37.5%	38.9%	1.4

[imjasonh]

/lgtm

[tekton-robot]

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[mattmoor]

/retest

Test doesn't look event related, and this code path should be inactive for e2es