NodeJoin Script: improve clean up message when using package manager

When re-running the node join script, the script refused to continue
because it detected teleport already on the system.
The script had a couple of instructions that removed teleport from the
system.
One of the steps is the removal of the teleport binary.
However, it would recommend the removal of the binaries even for systems
that had package managers. This fails because, even if the binaries
(teleport, tsh, tctl) are removed, the package manager will still refuse
to install teleport again because it was not removed from the package
manager database.

This PR changes the script, so that if it detects a package manager, it
will instead ask the user to remove the teleport package and not
directly removing the binaries.

lib/web/scripts/node-join/install.sh

@@ -230,15 +230,33 @@ log_important() {
 log_cleanup_message() {
     log_only "This script does not overwrite any existing settings or Teleport installations."
     log_only "Please clean up by running any of the following steps as necessary:"
+    if is_using_systemd; then
+        log_only "- stop teleport's service"
+        log_only "  - systemctl stop teleport"
+    fi
     log_only "- stop any running Teleport processes"
     log_only "  - pkill -f teleport"
     log_only "- remove any data under ${TELEPORT_DATA_DIR}, along with the directory itself"
     log_only "  - rm -rf ${TELEPORT_DATA_DIR}"
     log_only "- remove any configuration at ${TELEPORT_CONFIG_PATH}"
     log_only "  - rm -f ${TELEPORT_CONFIG_PATH}"
-    log_only "- remove any Teleport binaries (${TELEPORT_BINARY_LIST}) installed under ${TELEPORT_BINARY_DIR}"
-    for BINARY in ${TELEPORT_BINARY_LIST}; do EXAMPLE_DELETE_COMMAND+="${TELEPORT_BINARY_DIR}/${BINARY} "; done
-    log_only "  - rm -f ${EXAMPLE_DELETE_COMMAND}"
+    if check_exists apt; then
+        log_only "- remove teleport package"
+        log_only "  - apt remove teleport"
+    elif check_exists yum; then
+        log_only "- remove teleport package"
+        log_only "  - yum remove teleport"
+    elif check_exists dnf; then
+        log_only "- remove teleport package"
+        log_only "  - dnf remove teleport"
+    elif check_exists zypper; then
+        log_only "- remove teleport package"
+        log_only "  - zypper remove teleport"
+    else
+        log_only "- remove any Teleport binaries (${TELEPORT_BINARY_LIST}) installed under ${TELEPORT_BINARY_DIR}"
+        for BINARY in ${TELEPORT_BINARY_LIST}; do EXAMPLE_DELETE_COMMAND+="${TELEPORT_BINARY_DIR}/${BINARY} "; done
+        log_only "  - rm -f ${EXAMPLE_DELETE_COMMAND}"
+    fi
     if is_macos_host; then
         log_only "- unload and remove Teleport launchd config ${LAUNCHD_CONFIG_PATH}/${LAUNCHD_PLIST_FILE}"
         log_only "  - launchctl unload ${LAUNCHD_CONFIG_PATH}/${LAUNCHD_PLIST_FILE}"