smart rollup: private rollup has a max number of stakers at origination

Context

It was allowed to have bigger whitelist at the origination of the rollup than in a following update update. While this is not problematic this MR remove the difference and now whitelist can't be bigger at origination.

fix #6025 (closed)

Manually testing the MR

tries to originate a rollup with a whitelist of more than 194 element.

Checklist

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