• Revert "xds: reuse connections to the control plane across channels" added in 1.81.0 (#12887). If using xds heavily with many targets, then MAX_CONCURRENT_STREAMS to the control plane could be exceeded. This then prevents loading resources for new targets, which causes those channels to hang on name resolution. RPCs would see the nondescript "DEADLINE_EXCEEDED: Deadline Context was exceeded after Xs" or "DEADLINE_EXCEEDED: Deadline CallOptions was exceeded after Xs"