fix: Prevent generate new avail seed in roller migrate

[ItayLevyOfficial]

When updating the DA config in the v0.1.12 migrate, we first created a newAvail and then moved the avail config file to the new location. This caused generating a new avail seed and saving it only in the dymint.toml config.

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[VictorTrustyDev]

@ItayLevyOfficial how about a migration correct data for users which having the same issue? Is that necessary?

[ItayLevyOfficial]

@VictorTrustyDev we thought about it and decided it is unnecessary for now, since the new release was available only for a small amount of users and they can overcome it with roller config set da local