We should change the swappiness warning to 0 or 1 in the installer

Sometime ago we changed our docs to recommend a swappiness value of 1 for server deployments. See https://docs.couchbase.com/server/current/install/install-swap-space.html.

However, in the installer we still warn if the value is not set to zero. E.g. on RH systems:

SWAPPINESS=`cat /proc/sys/vm/swappiness`

if [ "$SWAPPINESS" -ne "0" ]

then

    cat <<EOF

Warning: Swappiness is not set to 0.

Please look at https://docs.couchbase.com/server/@@MAJ_MIN_VER@@/install/install-swap-space.html as for how to PERMANENTLY alter this setting.

EOF

fi

And we have similar behavior on Debian and related systems.

I suggest we change to warn if the swappiness value is not set to either zero or one.