Configure push mirroring to use the same ssh key for all projects

I am setting up push mirroring.

I made a backup of my gitlab-ce omnibus server and restored it on a server that I had just set up.

Then I proceeded to begin setting up the push mirroring. Which was not at all straightforward, but eventually I figured out how to get it working.

I have found that the ssh key used for each project on the source server is different. So if I have 30 projects, I am going to need to add 30 different ssh public keys to my admin user on the target server.

Can I configure the source server to use a single ssh key for push mirroring on all projects instead so the target server doesn’t need tons of keys? I did not see a way to do this.

Also, I would like to use a 521 bit ecdsa key instead of the rsa key that it seems to generate by default. Is that possible?

Running the latest (15.10.1) on both servers, which are Ubuntu 22.0.4.