Reader.has_message_available() returns True when no more messages are available on a compacted topic with tombstone messages

When reading a compacted topic with `is_read_compacted=True` `has_message_available` returns true even after all messages have been read when there is a tombstone message. This might be related to #199. As soon as any messages are added after compaction it behaves correctly again.

Python 3.12.4
pulsar-client 3.5.0

```python
url = "localhost"
topic = "tenant/namespace/topic"
client = pulsar.Client(pulsar_url)

producer = client.create_producer(topic)
producer.send(
b'message',
partition_key="1",
)
# tombstone message
producer.send(
b'',
partition_key="1",
)
# If there is only the tombstone message, then it returns False, presumably because the compacted topic is empty
producer.send(
b'message2',
partition_key="2",
)

# compact the topic here with "bin/pulsar-admin topics compact tenant/namespace/topic"

reader = client.create_reader(
topic=topic,
start_message_id=pulsar.MessageId.earliest,
is_read_compacted=True,
)

while reader.has_message_available():
msg = reader.read_next()
print(msg.data())
```
Once another message has been sent, the reader operates correctly again.

```python
producer.send(
b'message3',
partition_key="3",
)
while reader.has_message_available():
msg = reader.read_next()
print(msg.data())
```

Start by running the provided Python reproduction against a compacted topic containing a tombstone, using Reader.has_message_available() with is_read_compacted=True. Confirm that the reader reports availability after all messages are read, then verify that adding another message changes the behavior. Done means the method returns false once the compacted topic is exhausted, including when tombstone messages are present.

索引モデルが issue の本文から書いたものです。