remove GSN_STATISTICS_REQ and CONF

These are unused and have been since BK import. not needed.


ndb/include/kernel/GlobalSignalNumbers.h:
  remove STATISTICS_REQ and CONF
ndb/src/common/debugger/signaldata/SignalNames.cpp:
  remove signal names for STATISTICS_REQ and CONF (unused)
ndb/src/kernel/blocks/cmvmi/Cmvmi.cpp:
  remove unused STATISTICS signals
ndb/src/kernel/blocks/cmvmi/Cmvmi.hpp:
  remove unused STATISTICS signals