Remove `add_v17_message_authorizations` in `start-zetacored.sh` script

[lumtis]

Describe the Issue In the https://github.com/zeta-chain/node/pull/2118 PR, a add_v17_message_authorizations method is used in start-zetacored.sh in order to support upgrade tests.

In upgrade tests, the zetacored binary v16 will generate genesis containing authz authorizations for the previous messages for observers. This script is used to add the new v17 message names in the authorizations

After v17 upgrade, this function can be removed