"preinstall" script shouldn't sneaky update the global git config

[sergeys-opera]

Expected Behavior

"preinstall" script should only update the local git configuration. Or the developers should be instructed to update the global git config manually.

Current Behavior

"preinstall" script forces https instead of ssh for git globally for all the projects and not only for celo-monorepo: https://github.com/celo-org/celo-monorepo/blob/master/package.json#L8

This is what I get in my global git config after running the "preinstall" script:

$ git config --global --edit

[url "https://"]
        insteadOf = ssh://

This might lead to unexpected errors when fetching source code from other repositories that don't allow https.