Fix reporting unused_validators for DVT

[mksh]

We discovered that DVT enabled operator instances report sw_operator_unused_validator_keys incorrectly, always as zero ( #421 ).

This happens because logic that determines number of unused keys, skips keys that are not in the keystore (regardless whether it's loaded from Hashicorp vault or local filesystem). Within DVT setup, the local keystore contains BLS key shares instead of validator full keys, and the key shares have their derived public key different from a validator key, which leads to all keys that are in deposit data, being skipped because they do not match any of key share public keys.

Because it is not possible to heuristically determine whether the keys loaded are full validator keys or key shares, we propose to add new parameter RUNS_DVT_SETUP which will signalize to the unused keys logic that keys not present in keystore should not be skipped. Also, added the logic to override this setting to true in relayer setups that are configured to use DVT via --relayer-type parameter.