### What?

When a gen_batch_server process exits abnormally, proc_lib:exit_p/3
generates a crash report that includes the process mailbox contents
(via proc_lib:get_messages/1). The default OTP logger handler then
formats this crash report in the dying process itself
(logger_h_common:log_to_binary/2) using io_lib_pretty with potentially
unlimited depth and character limits.

For high-throughput gen_batch_server processes like the Ra WAL, the
mailbox can contain thousands of messages with large binary payloads
(e.g. AMQP message bodies). Pretty-printing these binaries byte-by-byte
via io_lib_pretty:print_length_binary causes unbounded memory growth,
observed at 10-25+ GB before the node runs out of memory.

The fix drains the mailbox after terminate/2 but before exit/1 or
erlang:raise/3 on every exit path. This way proc_lib's crash report
finds an empty mailbox, keeping the report small. The exit reason
semantics are preserved so supervisors still see the abnormal exit
and restart the process normally.

 ### Repro steps

**Without** this commit, the following repro steps caused RabbitMQ nodes to
run out of memory. In tanzu-rabbitmq:
1. put `rabbit_chaos` module in `deps/rabbit/src/`
2. `make start-cluster NODES=3 ENABLED_PLUGINS="rabbitmq_jms_management" FULL=1`
3.
```
omq amqp --uri amqp://localhost:5672/,amqp://localhost:5673/,amqp://localhost:5674/ \
                     --queues jms --queue-args 'x-selector-fields=*',x-queue-leader-locator=balanced \
                     -t /queues/jmsq-%d -T /queues/jmsq-%d -s '{{ randInt 1000 100000 }}' \
                     -x 10 -y 9 --consumer-credits 1000 \
                     --amqp-app-property 'color=red,blue,green,yellow' -c  1000 \
                     --amqp-jms-selector "color <> 'red'"
```
4.
```
for i in 1 2 3; do rabbitmqctl -n rabbit-$i eval 'rabbit_chaos:begin_jms_chaos().'; done
```

After 30-90 seconds, process memory of `ra_jms_queues_log_wal` grew huge
(several GBs).

This process had the following stacktrace:
```
./sbin/rabbitmqctl -n rabbit-3 eval 'Pid = whereis(ra_jms_queues_log_wal), erlang:process_info(Pid, [current_function, current_location, current_stacktrace, initial_call, message_queue_len, registered_name, status,stack_size, backtrace]).'
```
shows the following:
```
[{current_function,{lists,reverse,2}},
 {current_location,{lists,reverse,2,[]}},
 {current_stacktrace,[{lists,reverse,1,[{file,"lists.erl"},{line,298}]},
                      {io_lib,write_binary,3,[{file,"io_lib.erl"},{line,860}]},
                      {io_lib_pretty,print_length_binary,7,
                                     [{file,"io_lib_pretty.erl"},{line,1139}]},
                      {io_lib_pretty,print_length_list1,7,
                                     [{file,"io_lib_pretty.erl"},{line,1058}]},
                      {io_lib_pretty,print_length_list1,7,
                                     [{file,"io_lib_pretty.erl"},{line,1059}]},
                      {io_lib_pretty,print_length_list,7,
                                     [{file,"io_lib_pretty.erl"},{line,1043}]},
                      {io_lib_pretty,print_length,7,
                                     [{file,"io_lib_pretty.erl"},
                                      {line,906}]}]},
 {initial_call,{proc_lib,init_p,5}},
 {message_queue_len,5479},
 {registered_name,ra_jms_queues_log_wal},
 {status,running},
 {stack_size,443},

...

0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0... \ny(9)     Catch 0x000070608720a8e9 (logger_backend:call_handlers/3 + 665)\n\n0x0000705ce667de68 Return addr 0x0000706087248774 (proc_lib:exit_p/3 + 364)\ny(0)     [{gen_batch_server,handle_batch_result,3,[{file,\"src/gen_batch_server.erl\"},{line,424}]},{gen_batch_server,loop_batched,2,[{file,\"src/gen_batch_server.erl\"},{line,354}]},{proc_lib,init_p_do_apply,3,[{file,\"proc_lib.erl\"},{line,333}]}]\ny(1)     chaos\ny(2)     exit\n\n0x0000705ce667de88 Return addr 0x0000706087001248 (<terminate process normally>)\n">>}]
```