/usr/sbin/rabbitmq-plugins is in rabbitmq-server 3.2.4-1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 | #!/bin/sh
##  The contents of this file are subject to the Mozilla Public License
##  Version 1.1 (the "License"); you may not use this file except in
##  compliance with the License. You may obtain a copy of the License
##  at http://www.mozilla.org/MPL/
##
##  Software distributed under the License is distributed on an "AS IS"
##  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
##  the License for the specific language governing rights and
##  limitations under the License.
##
##  The Original Code is RabbitMQ.
##
##  The Initial Developer of the Original Code is GoPivotal, Inc.
##  Copyright (c) 2007-2013 GoPivotal, Inc.  All rights reserved.
##
# Escape spaces and quotes, because shell is revolting.
for arg in "$@" ; do
	# Escape quotes in parameters, so that they're passed through cleanly.
	arg=$(sed -e 's/"/\\"/g' <<-END
		$arg
		END
	)
	CMDLINE="${CMDLINE} \"${arg}\""
done
cd /var/lib/rabbitmq
SCRIPT=`basename $0`
if [ `id -u` = `id -u rabbitmq` -a "$SCRIPT" = "rabbitmq-server" ] ; then
    /usr/lib/rabbitmq/bin/rabbitmq-server "$@"  > "/var/log/rabbitmq/startup_log" 2> "/var/log/rabbitmq/startup_err"
elif [ `id -u` = `id -u rabbitmq` -o "$SCRIPT" = "rabbitmq-plugins" ] ; then
    /usr/lib/rabbitmq/bin/${SCRIPT} "$@"
elif [ `id -u` = 0 ] ; then
    su rabbitmq -s /bin/sh -c "/usr/lib/rabbitmq/bin/${SCRIPT} ${CMDLINE}"
else
    /usr/lib/rabbitmq/bin/${SCRIPT}
    echo
    echo "Only root or rabbitmq should run ${SCRIPT}"
    echo
    exit 1
fi
 |