disable running Cache VOL for netcdf4 + log option

[wkliao]

Testing netcdf4 + log layout option has been disabled for Cache VOL connector.
See the github issue at Cache VOL repo at HDFGroup/vol-cache#18

The source codes below show the location in test.sh that disables the test.
Note the environment variable HDF5_VOL_CONNECTOR is overwritten if set by users.

E3SM-IO/test.sh

Lines 102 to 116 in 988537c

	elif test "x${ap[0]}" = xnetcdf4 ; then
	FILE_EXT="nc4"
	saved_HDF5_PLUGIN_PATH=$HDF5_PLUGIN_PATH
	saved_HDF5_VOL_CONNECTOR=$HDF5_VOL_CONNECTOR
	if test "x${ap[1]}" = xlog ; then
	# This option requires the two VOL environment variables to be set.
	export HDF5_PLUGIN_PATH="$LOGVOL_LIB_PATH"
	export HDF5_VOL_CONNECTOR="LOG under_vol=0;under_info={}"
	# Decomposition file must be read with native VOL, use nc file
	IN_FILE+=".nc"
	else
	IN_FILE+=".${FILE_EXT}"
	unset HDF5_PLUGIN_PATH
	unset HDF5_VOL_CONNECTOR
	fi