profile.d: prepend purple hexagon to PS1 rather than overwriting it

More importantly it means the traditional Red Hat style prompt is
not forced onto all other OS toolboxes too.

A space is added after the hexagon since vte tends to render it too  big
at least with google-noto-color-emoji-fonts.

containers#1517

Signed-off-by: Jens Petersen <petersen@redhat.com>

profile.d/toolbox.sh

@@ -48,8 +48,8 @@ fi
 
 if [ -f /run/.containerenv ] \
    && [ -f /run/.toolboxenv ]; then
-    [ "${BASH_VERSION:-}" != "" ] && PS1=$(printf "\[\033[35m\]⬢\[\033[0m\]%s" "[\u@\h \W]\\$ ")
-    [ "${ZSH_VERSION:-}" != "" ] && PS1=$(printf "\033[35m⬢\033[0m%s" "[%n@%m]%~%# ")
+    [ -n "${BASH_VERSION}" ] && PS1="\[\e[35m\]⬢\[\e[0m\] $PS1"
+    [ -n "${ZSH_VERSION:-}" ] && PS1=$(printf "\033[35m⬢\033[0m %s" "$PS1")
 
     if ! [ -f "$toolbox_welcome_stub" ]; then
         echo ""