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

This also avoids the need to have separate definitions for bash and zsh

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

#1517

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

profile.d/toolbox.sh

@@ -48,9 +48,9 @@ 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]%~%# ")
-
+    if [ -n "${BASH_VERSION:-}" ] || [ -n "${ZSH_VERSION:-}" ]; then
+        PS1="\[\e[35m\]⬢ \[\e[0m\]$PS1"
+    fi
     if ! [ -f "$toolbox_welcome_stub" ]; then
         echo ""
         echo "Welcome to the Toolbx; a container where you can install and run"