ctdb-scripts: Avoid ShellCheck warning SC2164

ctdb-scripts: Avoid ShellCheck warning SC2164

SC2164 (warning): Use 'cd ... || exit' or 'cd ... || return' in case cd fails.

A problem can only occur if /etc/ctdb/ or an important subdirectory is
removed, which means the script itself would not be found.  Use && to
silence ShellCheck.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>