Update etherpad to 1.9.1

Update etherpad to 1.9.1 via updates to our downstream Dockerfile. These
updates should match the upstream Dockerfile pretty closely.

We use the node:18-bookworm-slim image to align with upstreams
node:18-slim image (but we are specific about the platform).
We add a configurable TIMEZONE section from upstream that we don't use
but keeps us in sync. Finally we updated our settings to for userName
and userColor to be null to match upstream defaults. Keeping the old
false values creates odd behavior around choosing names and colors when
first joining a pad.

Change-Id: Ic87d6f9d524515397386b32c147681d128d972cc

docker/etherpad/Dockerfile

@@ -22,9 +22,16 @@
 #
 # Author: muxator
 
-FROM node:14-buster-slim
+FROM node:18-bookworm-slim
 LABEL maintainer="infra-root@openstack.org"
 
+ARG TIMEZONE=
+RUN \
+  [ -z "${TIMEZONE}" ] || { \
+    ln -sf /usr/share/zoneinfo/"${TIMEZONE#/usr/share/zoneinfo/}" /etc/localtime; \
+    dpkg-reconfigure -f noninteractive tzdata; \
+  }
+
 # plugins to install while building the container. By default no plugins are
 # installed.
 # If given a value, it has to be a space-separated, quoted list of plugin names.
@@ -93,7 +100,7 @@ USER etherpad
 
 RUN git clone https://github.com/ether/etherpad-lite ${EP_DIR}
 WORKDIR "${EP_DIR}"
-RUN git checkout 1.8.18
+RUN git checkout v1.9.1
 
 # Plugins must be installed before installing Etherpad's dependencies, otherwise
 # npm will try to hoist common dependencies by removing them from

playbooks/roles/etherpad/templates/settings.json.j2

@@ -43,8 +43,8 @@
     "showChat":         true,
     "showLineNumbers":  true,
     "useMonospaceFont": false,
-    "userName":         false,
-    "userColor":        false,
+    "userName":         null,
+    "userColor":        null,
     "rtl":              false,
     "alwaysShowChat":   true,
     "chatAndUsers":     false,