refactor(examples) Update opacus example #16200

Job	Run time
Build, test and upload wheel	1m 17s
Framework / e2e-bare	3m 30s
Template / numpy	48s
Framework / e2e-bare-https	1m 6s
Strategy / FedMedian	1m 13s
Framework / e2e-bare-auth	48s
Template / pytorch	2m 36s
Strategy / FedTrimmedAvg	1m 12s
Template / tensorflow	1m 41s
Framework / e2e-jax	1m 29s
Strategy / QFedAvg	1m 7s
Template / jax	59s
Framework / e2e-pytorch	2m 25s
Strategy / FaultTolerantFedAvg	1m 16s
Template / sklearn	1m 21s
Framework / e2e-tensorflow	4m 43s
Strategy / FedAvgM	1m 12s
Framework / e2e-opacus	2m 39s
Strategy / FedAdam	1m 5s
Framework / e2e-pytorch-lightning	1m 36s
Strategy / FedAdagrad	1m 12s
Framework / e2e-scikit-learn	1m 31s
Framework / e2e-fastai	2m 35s
Strategy / FedYogi	1m 12s
Framework / e2e-pandas	1m 16s
	41m 49s

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