[Bugs] Sometime accept for the SCTP socket fails

[ShouheiNishi]

Describe the bug

Sometime accept for the SCTP socket fails in AMF.

To Reproduce

Steps to reproduce the behavior:

1. Apply this patch

diff --git a/test/registration_test.go b/test/registration_test.go
index 761e064..8c0e4f1 100644
--- a/test/registration_test.go
+++ b/test/registration_test.go
@@ -64,6 +64,11 @@ func TestRegistration(t *testing.T) {
        var recvMsg = make([]byte, 2048)

        // RAN connect to AMF
+       for i := 0; i < 1000; i++ {
+               conn, err := test.ConnectToAmf(amfN2Ipv4Addr, ranN2Ipv4Addr, 38412, 9487)
+               assert.Nil(t, err)
+               conn.Close()
+       }
        conn, err := test.ConnectToAmf(amfN2Ipv4Addr, ranN2Ipv4Addr, 38412, 9487)
        assert.Nil(t, err)

2. Run command ./test.sh -o TestRegistration

Environment (please complete the following information):

• free5GC Version: 3.4.1
• OS: Ubuntu 20.04.6 LTS
• Kernel version: 5.15.0-102-generic
• go version: go1.22.2

Additional context

It seems that this issue is caused by free5gc/sctp@097e517.
In this issue case, raw SCTP socket may be leaked.

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