[neutron][networking-midonet] Propose to EOL stable/pike, stable/queens and stable/rocky branches of networking-midonet

Hi,

The older than rocky branches of networking-midonet are broken, as it seems that the last merge on stable/rocky and stable/queens happened a year ago, and even the master branch of networking-midonet is not maintained. Considering the above I propose to make stable/rocky, stable/queens, stable/pike branches End Of Life.

I will wait until the end of next week for anyone who would like to maybe step up as maintainer of those branches and who would at least try to fix CI of them. If there will be no volunteers for that, I will EOL those branches in networking-midonet.

Lajos Katona (lajoskatona)