Workaround for getStorageAt() bug in Hardhat 2.9.5 for gnosis external test

[cameel]

Gnosis external test started failing due to and extra sanity check introduced by Hardhat 2.9.5:

Besides that, now the eth_getStorageAt method is spec-compliant. This means that the storage slot argument must have a length of 32 bytes (a hex-encoded, 0x-prefixed string of length 66).

This makes gnosis job fail in some PRs. E.g. 1059920:

 1) Migration
       migrate
         can migrate:
     InvalidArgumentsError: Errors encountered in param 1: Storage slot argument must have a length of 66 ("0x" + 32 bytes), but '0x6' has a length of 3

I have submitted an upstream fix (safe-global/safe-smart-account#404) but unfortunately Hardhat has a bug and does not really accept properly padded storage address either (NomicFoundation/hardhat#2709).

For now the simplest workaround is to stay at 2.9.4.

[ekpyron]

Needs a rebase, if we want the archlinux test to pass. But we should see whether it fixes the gnosis run either way. If it does, we can merge.

[cameel]

Gnosis test passed so I'll rebase.