Install contractGovernor only once in priceFeed replacement proposal

[Chris-Hibbert]

What is the Problem Being Solved?

@dckc pointed out that #10163 was installing the contractGovernor twice. I don't think this will break anything, but it will make verifying the connectivity of the governance components more difficult.

Description of the Design

Install it once in whichever proposal will run first, and pass it to the other proposals via a new (temporary) name in the promiseSpace. If not passed sub rosa like this, the second proposal would probably get the previous value, since the promise has already been resolved.

Security Considerations

This affects legibility of the governed contracts.

Scaling Considerations

inconsequential.

Test Plan

Ensure that the two installations are the same.

Upgrade Considerations

This is not required to be included with the priceFeed update (#10074), but it would be nice.
It has its impact during upgrade.