respect VIRTUAL_ENV_PROMPT if its value is different from the default (#1718)

internal/p10k.zsh

@@ -4224,7 +4224,11 @@ prompt_virtualenv() {
     msg="${_p9k__ret//\%/%%} "
   fi
   local v=${VIRTUAL_ENV:t}
-  [[ $v == $~_POWERLEVEL9K_VIRTUALENV_GENERIC_NAMES ]] && v=${VIRTUAL_ENV:h:t}
+  if [[ $VIRTUAL_ENV_PROMPT == '('?*') ' && $VIRTUAL_ENV_PROMPT != "($v) " ]]; then
+    v=$VIRTUAL_ENV_PROMPT[2,-3]
+  elif [[ $v == $~_POWERLEVEL9K_VIRTUALENV_GENERIC_NAMES ]]; then
+    v=${VIRTUAL_ENV:h:t}
+  fi
   msg+="$_POWERLEVEL9K_VIRTUALENV_LEFT_DELIMITER${v//\%/%%}$_POWERLEVEL9K_VIRTUALENV_RIGHT_DELIMITER"
   case $_POWERLEVEL9K_VIRTUALENV_SHOW_WITH_PYENV in
     false)