long_tezt: Fix block validation initialization by upgrading storage

The block validation benchmark is currently failing continuously as the datadir was not upgraded since storage was upgraded to 1.0.

[09:03:55.242] [node2] tezos-node: Error:
[09:03:55.242] [node2]               The data directory version is too old.
[09:03:55.242] [node2]               Found '0.8', expected '1.0'.
[09:03:55.242] [node2]               It needs to be upgraded with `tezos-node upgrade storage`.

This little patch proposes to add a storage upgrade at the start of the benchmarks in order for them to be resilient to future storage upgrades.

This was tested in local using a datadir in 0.8 to ensure that this can work properly. Don't hesitate to ask me a copy of this datadir to be able to test on your side.

Checklist

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