fix: [3.3.6] memory leak and use-after-free crash

[DuanKuanJun]

Description

Issue(s)

• Close/close/Fix/fix/Resolve/resolve: Issue Link

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[Copilot]

Pull request overview

This PR addresses memory-lifecycle issues (leaks / potential use-after-free) in client async DDL execution and executor sys-table scan flows, and tweaks CI upgrade compatibility download caching.

Changes:

• Executor: free and clear pInfo->pRsp in sysTableScanFromMNode() to avoid stale pointers after freeing response buffers.
• Client: free pQuery->pCmdMsg immediately after asyncSendMsgToServer() in asyncExecDdlQuery() to prevent orphaned allocations during shutdown/atexit teardown.
• CI: lower cached “valid file” size threshold from 30M to 10M for upgrade compatibility artifact reuse.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
test/ci/run_upgrade_compat.sh	Adjusts local cache validation threshold for downloaded “green versions”.
source/libs/executor/src/sysscanoperator.c	Clears pInfo->pRsp when freeing response to avoid dangling pointers.
source/client/src/clientImpl.c	Frees pQuery->pCmdMsg earlier in async DDL path to prevent leaks during teardown.

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[gemini-code-assist]

Code Review

This pull request introduces memory management improvements by explicitly freeing pQuery->pCmdMsg in the client implementation and adopting taosMemoryFreeClear for response buffers in the system scan operator. It also reduces the cache validation size threshold in the CI upgrade script. Feedback indicates that the script's cache validation heuristic is fragile and recommends using a more robust method like checksums or manifest files to ensure environment consistency.