[RDB Scaling] Have old RDB recognize when new RDB is active

[eugenetemlock]

there is a function called: list_kx_cluster -> shows a list of clusters and their states

Update as of 2023.11.28, where new RDB proc should signal the old RDB cluster when subscribing to the TP:
As of now, TP is unavailable so use Feed as subtitute
Best to add logic of having the Feed obtaining cluster info from the discovery
Not sure if the .dotz allows for .z.po functionality, so as a workaround will need to use frequent polling
- If allowd, then on .z.po event signal the old cluster. You should also get the handle or something from the discovery if possible