fix try_create_uring() probe release for ASAN

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==93534==ERROR: AddressSanitizer: attempting free on address which was not malloc()-ed: 0x7f676abad010 in thread T0
    #0 0x7f677fedfdc2 in __interceptor_free /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:52
    scylladb#1 0x7f6776e81776 in operator() /home/sitano/Projects/seastar/src/core/reactor_backend.cc:1242
    scylladb#2 0x7f6776e884a4 in ~deferred_action /home/sitano/Projects/seastar/include/seastar/util/defer.hh:67
    scylladb#3 0x7f6776e82d31 in try_create_uring /home/sitano/Projects/seastar/src/core/reactor_backend.cc:1253
    scylladb#4 0x7f6776e83e39 in detect_io_uring /home/sitano/Projects/seastar/src/core/reactor_backend.cc:1288
    scylladb#5 0x7f6776e85113 in seastar::reactor_backend_selector::available() /home/sitano/Projects/seastar/src/core/reactor_backend.cc:2039
    scylladb#6 0x7f67773be492 in seastar::reactor_options::reactor_options(seastar::program_options::option_group*) /home/sitano/Projects/seastar/src/core/reactor.cc:3782
    scylladb#7 0x7f6776f04c32 in seastar::app_template::seastar_options::seastar_options() /home/sitano/Projects/seastar/src/core/app-template.cc:70
    scylladb#8 0x7f6776f04040 in seastar_options_from_config /home/sitano/Projects/seastar/src/core/app-template.cc:58
    scylladb#9 0x7f6776f0704f in seastar::app_template::app_template(seastar::app_template::config) /home/sitano/Projects/seastar/src/core/app-template.cc:108
    scylladb#10 0x55a5ff597a6e in main /home/sitano/Projects/seastar/demos/hello-world.cc:30
    scylladb#11 0x7f676f03984f  (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)
    scylladb#12 0x7f676f039909 in __libc_start_main (/usr/lib/libc.so.6+0x23909) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)
    scylladb#13 0x55a5ff597614 in _start (/home/sitano/Projects/seastar/build/debug/demos/hello-world_demo+0xf0614) (BuildId: cbf8a43d1565f3bf0a48cdfb43a11ce16d7a9bc1)

Address 0x7f676abad010 is a wild pointer inside of access range of size 0x000000000001.
SUMMARY: AddressSanitizer: bad-free /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:52 in __interceptor_free
==93534==ABORTING

src/core/reactor_backend.cc

@@ -1239,7 +1239,7 @@ try_create_uring(unsigned queue_len, bool throw_on_error) {
         maybe_throw(std::runtime_error("unable to create io_uring probe"));
         return std::nullopt;
     }
-    auto free_probe = defer([&] () noexcept { ::free(probe); });
+    auto free_probe = defer([&] () noexcept { ::io_uring_free_probe(probe); });
 
     for (auto op : required_ops) {
         if (!io_uring_opcode_supported(probe, op)) {