[mdns-avahi] utilize Avahi events for complete result handling

This commit enhances `Mdns::Publisher` using Avahi to utilize the
events `AVAHI_BROWSER_ALL_FOR_NOW` and `CACHE_EXHAUSTED`, which
notify that all records have been processed and no further results
are expected in the near future.

This improvement prevents premature "resolved" callbacks after
receiving only the initial IPv6 address, thereby improving host and
service address resolution. The `Publisher` now waits for these
events to ensure it gathers all available addresses from the
cache and query responses before signaling resolved callback.

src/mdns/mdns_avahi.cpp

@@ -1367,13 +1367,11 @@ void PublisherAvahi::ServiceResolver::HandleResolveHostResult(AvahiRecordBrowser
     OTBR_UNUSED_VARIABLE(aRecordBrowser);
     OTBR_UNUSED_VARIABLE(aInterfaceIndex);
     OTBR_UNUSED_VARIABLE(aProtocol);
-    OTBR_UNUSED_VARIABLE(aEvent);
     OTBR_UNUSED_VARIABLE(aClazz);
     OTBR_UNUSED_VARIABLE(aType);
     OTBR_UNUSED_VARIABLE(aFlags);
 
     Ip6Address address;
-    bool       resolved   = false;
     int        avahiError = AVAHI_OK;
 
     otbrLog(aEvent != AVAHI_BROWSER_FAILURE ? OTBR_LOG_INFO : OTBR_LOG_WARNING, OTBR_LOG_TAG,
@@ -1400,10 +1398,9 @@ void PublisherAvahi::ServiceResolver::HandleResolveHostResult(AvahiRecordBrowser
     {
         mInstanceInfo.RemoveAddress(address);
     }
-    resolved = true;
 
 exit:
-    if (resolved)
+    if ((aEvent == AVAHI_BROWSER_CACHE_EXHAUSTED) || (aEvent == AVAHI_BROWSER_ALL_FOR_NOW))
     {
         // NOTE: This `HostSubscrption` object may be freed in `OnHostResolved`.
         mPublisherAvahi->OnServiceResolved(mType, mInstanceInfo);
@@ -1498,13 +1495,11 @@ void PublisherAvahi::HostSubscription::HandleResolveResult(AvahiRecordBrowser
 {
     OTBR_UNUSED_VARIABLE(aRecordBrowser);
     OTBR_UNUSED_VARIABLE(aProtocol);
-    OTBR_UNUSED_VARIABLE(aEvent);
     OTBR_UNUSED_VARIABLE(aClazz);
     OTBR_UNUSED_VARIABLE(aType);
     OTBR_UNUSED_VARIABLE(aFlags);
 
     Ip6Address address;
-    bool       resolved   = false;
     int        avahiError = AVAHI_OK;
 
     otbrLog(aEvent != AVAHI_BROWSER_FAILURE ? OTBR_LOG_INFO : OTBR_LOG_WARNING, OTBR_LOG_TAG,
@@ -1536,10 +1531,9 @@ void PublisherAvahi::HostSubscription::HandleResolveResult(AvahiRecordBrowser
     mHostInfo.mNetifIndex = static_cast<uint32_t>(aInterfaceIndex);
     // TODO: Use a more proper TTL
     mHostInfo.mTtl = kDefaultTtl;
-    resolved       = true;
 
 exit:
-    if (resolved)
+    if ((aEvent == AVAHI_BROWSER_CACHE_EXHAUSTED) || (aEvent == AVAHI_BROWSER_ALL_FOR_NOW))
     {
         // NOTE: This `HostSubscrption` object may be freed in `OnHostResolved`.
         mPublisherAvahi->OnHostResolved(mHostName, mHostInfo);