Check existence of inbox before cleaning when client connecting with CleanStart=True

[popduke]

The "CleanStart = true" with a non-empty client ID requires clearing the previous session, which may trigger a write to the inbox store regardless of whether a previous session actually exists. To reduce unnecessary overhead, we can first check for the existence of the session—a lightweight read—and only perform the clear operation if necessary. This approach can significantly reduce inbox store overhead in typical scenarios.

[coveralls]

Pull Request Test Coverage Report for Build 16337327511

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 61 unchanged lines in 10 files lost coverage.
• Overall coverage increased (+0.04%) to 63.239%

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Files with Coverage Reduction	New Missed Lines	%
org/apache/bifromq/basecluster/memberlist/AutoDropper.java	1	82.3%
org/apache/bifromq/basecluster/transport/TCPTransport.java	1	87.06%
org/apache/bifromq/basecrdt/core/internal/CausalCRDTInflater.java	1	93.07%
org/apache/bifromq/basecrdt/store/AntiEntropy.java	1	84.21%
org/apache/bifromq/dist/trie/TopicFilterIterator.java	1	70.23%
org/apache/bifromq/mqtt/handler/MQTTPersistentSessionHandler.java	1	74.57%
org/apache/bifromq/basecluster/fd/FailureDetector.java	2	88.16%
org/apache/bifromq/basecrdt/service/CRDTCluster.java	2	81.91%
org/apache/bifromq/basekv/raft/RaftNodeState.java	6	90.95%
org/apache/bifromq/mqtt/handler/MQTTConnectHandler.java	45	77.73%

Totals
Change from base Build 16309881962:	0.04%
Covered Lines:	23338
Relevant Lines:	35676

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💛 - Coveralls