machine: fix a memory leak when showing multiple machines

+ machinectl status long-running long-running long-running
=================================================================
==986==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 1568 byte(s) in 2 object(s) allocated from:
    #0 0x7fe57caba097 in calloc (/lib64/libasan.so.8+0xba097)
    #1 0x7fe57b891e8e in message_from_header ../src/libsystemd/sd-bus/bus-message.c:372
    #2 0x7fe57b892dfd in bus_message_from_malloc ../src/libsystemd/sd-bus/bus-message.c:421
    #3 0x7fe57b9089a8 in bus_socket_make_message ../src/libsystemd/sd-bus/bus-socket.c:1165
    #4 0x7fe57b90affe in bus_socket_read_message ../src/libsystemd/sd-bus/bus-socket.c:1294
    #5 0x7fe57b92db71 in bus_read_message ../src/libsystemd/sd-bus/sd-bus.c:2082
    #6 0x7fe57b933352 in sd_bus_call ../src/libsystemd/sd-bus/sd-bus.c:2483
    #7 0x7fe57b84da61 in sd_bus_call_methodv ../src/libsystemd/sd-bus/bus-convenience.c:183
    #8 0x7fe57b2789e8 in bus_call_method ../src/shared/bus-locator.c:109
    #9 0x40f71c in show_machine ../src/machine/machinectl.c:713
    #10 0x7fe57b65c8cf in dispatch_verb ../src/shared/verbs.c:103
    #11 0x42e9ce in machinectl_main ../src/machine/machinectl.c:2980
    #12 0x42ebf9 in run ../src/machine/machinectl.c:3005
    #13 0x42ed1f in main ../src/machine/machinectl.c:3008
    #14 0x7fe579e4a50f in __libc_start_call_main (/lib64/libc.so.6+0x2750f)
Indirect leak of 234 byte(s) in 2 object(s) allocated from:
    #0 0x7fe57cab95b5 in __interceptor_realloc.part.0 (/lib64/libasan.so.8+0xb95b5)
    #1 0x7fe57b909822 in bus_socket_read_message ../src/libsystemd/sd-bus/bus-socket.c:1214
    #2 0x7fe57b92db71 in bus_read_message ../src/libsystemd/sd-bus/sd-bus.c:2082
    #3 0x7fe57b933352 in sd_bus_call ../src/libsystemd/sd-bus/sd-bus.c:2483
    #4 0x7fe57b84da61 in sd_bus_call_methodv ../src/libsystemd/sd-bus/bus-convenience.c:183
    #5 0x7fe57b2789e8 in bus_call_method ../src/shared/bus-locator.c:109
    #6 0x40f71c in show_machine ../src/machine/machinectl.c:713
    #7 0x7fe57b65c8cf in dispatch_verb ../src/shared/verbs.c:103
    #8 0x42e9ce in machinectl_main ../src/machine/machinectl.c:2980
    #9 0x42ebf9 in run ../src/machine/machinectl.c:3005
    #10 0x42ed1f in main ../src/machine/machinectl.c:3008
    #11 0x7fe579e4a50f in __libc_start_call_main (/lib64/libc.so.6+0x2750f)
Indirect leak of 4 byte(s) in 2 object(s) allocated from:
    #0 0x7fe57ca7243b in strdup (/lib64/libasan.so.8+0x7243b)
    #1 0x7fe57b8c1543 in message_parse_fields ../src/libsystemd/sd-bus/bus-message.c:4125
    #2 0x7fe57b893586 in bus_message_from_malloc ../src/libsystemd/sd-bus/bus-message.c:443
    #3 0x7fe57b9089a8 in bus_socket_make_message ../src/libsystemd/sd-bus/bus-socket.c:1165
    #4 0x7fe57b90affe in bus_socket_read_message ../src/libsystemd/sd-bus/bus-socket.c:1294
    #5 0x7fe57b92db71 in bus_read_message ../src/libsystemd/sd-bus/sd-bus.c:2082
    #6 0x7fe57b933352 in sd_bus_call ../src/libsystemd/sd-bus/sd-bus.c:2483
    #7 0x7fe57b84da61 in sd_bus_call_methodv ../src/libsystemd/sd-bus/bus-convenience.c:183
    #8 0x7fe57b2789e8 in bus_call_method ../src/shared/bus-locator.c:109
    #9 0x40f71c in show_machine ../src/machine/machinectl.c:713
    #10 0x7fe57b65c8cf in dispatch_verb ../src/shared/verbs.c:103
    #11 0x42e9ce in machinectl_main ../src/machine/machinectl.c:2980
    #12 0x42ebf9 in run ../src/machine/machinectl.c:3005
    #13 0x42ed1f in main ../src/machine/machinectl.c:3008
    #14 0x7fe579e4a50f in __libc_start_call_main (/lib64/libc.so.6+0x2750f)
SUMMARY: AddressSanitizer: 1806 byte(s) leaked in 6 allocation(s).

src/machine/machinectl.c

@@ -687,9 +687,7 @@ static int show_machine_properties(sd_bus *bus, const char *path, bool *new_line
 }
 
 static int show_machine(int argc, char *argv[], void *userdata) {
-
         _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
-        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
         bool properties, new_line = false;
         sd_bus *bus = ASSERT_PTR(userdata);
         int r = 0;
@@ -708,6 +706,7 @@ static int show_machine(int argc, char *argv[], void *userdata) {
         }
 
         for (int i = 1; i < argc; i++) {
+                _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
                 const char *path = NULL;
 
                 r = bus_call_method(bus, bus_machine_mgr, "GetMachine", &error, &reply, "s", argv[i]);