xds-server: Create informers before starting informer factory

[cheahjs]

What type of PR is this?
/kind bug

What this PR does / Why we need it:

Fixes the Kubernetes controller implementation of the xds management server. Without the fix, the controller isn't able to list any GameServers or Pods in the cluster, and doesn't update connected Quilkin instances with endpoints.

The informer factory only starts informers that were already requested when Start() is called. The informers are requested when getting the Lister for a specific type. As we are calling Lister() after Start(), the informer never watches for the resources, and List() will always return the empty list.

Which issue(s) this PR fixes:

Special notes for your reviewer:

[quilkin-bot]

Build Succeeded 🥳

Build Id: 763ab32b-929f-4455-bd85-11d7bbfcaecc

To build this version:

git fetch [email protected]:googleforgames/quilkin.git pull/446/head:pr_446 && git checkout pr_446
cargo build

[XAMPPRocky]

Thank you for your PR! LGTM, but I'll wait for @markmandel || @iffyio to have a look before merging.

[iffyio]

LGTM! The order of things got shifted wrong in the pr it seems, Thanks for finding and fixing it 🎉