fix: UDR panic/crash paths for #919 #920 #922 #923

[Zach1113]

Remove AMF Subscription Panic: free5gc/free5gc#919, free5gc/free5gc#920

File: internal/sbi/processor/event_amf_subscription_info_document.go

Problem:

• The code continued execution even when UE state or subsId was missing.
• It then asserted/dereferenced nil values, causing panic.

Fix:

• Return immediately after USER_NOT_FOUND.
• Return immediately after SUBSCRIPTION_NOT_FOUND.
• Guard the map value with eeSub == nil check before reading AmfSubscriptionInfos.

---

Provisioned Data Panic: free5gc/free5gc#922

File: internal/sbi/processor/provisioned_data_document.go

Problem:

• provisionedDataSets.SmData is a pointer and was not initialized before assigning IndividualSmSubsData.
• Also, DNN rewrite loop modified a range-copy, so updates were not persisted.

Fix:

• Initialize SmData when nil before writing into it.
• Iterate by index (for i := range tmp) and update tmp[i] directly.

---

On-Data-Change Callback Crash: free5gc/free5gc#923

File: internal/sbi/processor/callback.go

Problem:

• DataChangeNotify pointer inside request struct was never initialized before field writes.
• Panic recovery used Fatalf, which terminates the process.

Fix:

• Build request with initialized DataChangeNotify object.
• Change recover logging from Fatalf to Errorf.

[roundspring2003]

@Alonza0314 Test All pass