maintainers: resign from keepalive, metrics and ethtool
maintainers: resign from keepalive, metrics and ethtool

After today I will no longer be with Intel, so I am
removing my name from all related maintainer roles.

Signed-off-by: Remy Horton <34c343e92f0e27f7a8e26a1d8d2146ae7c7dd1a3@intel.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk