fix: guard FFIPackedWriter against double close to prevent heap-use-after-free

[sunby]

Add nil guard and nil-out cWriterHandle/cProperties after close in FFIPackedWriter, matching the FFIPackedReader fix in #48473.

issue: #48560

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: sunby
To complete the pull request process, please assign czs007 after the PR has been reviewed.
You can assign the PR to them by writing /assign @czs007 in a comment when ready.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• internal/storagev2/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[sre-ci-robot]

[ci-v2-notice]
Notice: New ci-v2 system is enabled for this PR.

To rerun ci-v2 checks, comment with:

• /ci-rerun-code-check // for ci-v2/code-check
• /ci-rerun-build // for ci-v2/build
• /ci-rerun-build-all // for ci-v2/build-all (multi-arch builds)
• /ci-rerun-buildenv // for ci-v2/build-env (build milvus-env builder images)
• /ci-rerun-ut-integration // for ci-v2/ut-integration, will rerun ci-v2/build
• /ci-rerun-ut-go // for ci-v2/ut-go, will rerun ci-v2/build
• /ci-rerun-ut-cpp // for ci-v2/ut-cpp
• /ci-rerun-ut // for all ci-v2/ut-integration, ci-v2/ut-go, ci-v2/ut-cpp, will rerun ci-v2/build
• /ci-rerun-e2e-arm // for ci-v2/e2e-arm
• /ci-rerun-e2e-default // for ci-v2/e2e-default
• /ci-rerun-ciloop // for ci-v2/ciloop (build + unit tests in one pipeline)
• /ci-rerun-gosdk // for ci-v2/go-sdk (Go SDK E2E tests, AMD)
• /ci-rerun-gosdk-arm // for ci-v2/go-sdk-arm (Go SDK E2E tests, ARM)

If you have any questions or requests, please contact @zhikunyao.

[sunby]

/ci-rerun-code-check

[sunby]

/ci-rerun-code-check

[sunby]

/ci-rerun-code-check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.01%. Comparing base (d02e19d) to head (af4dafc).

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #48561       +/-   ##
===========================================
+ Coverage   77.66%   84.01%    +6.35%     
===========================================
  Files        2112      627     -1485     
  Lines      351497   104217   -247280     
===========================================
- Hits       272974    87554   -185420     
+ Misses      70204    16663    -53541     
+ Partials     8319        0     -8319     

Components	Coverage Δ
Client	∅ <ø> (∅)
Core	84.01% <ø> (-0.01%)	⬇️
Go	∅ <ø> (∅)
see 1486 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[sunby]

/ci-rerun-code-check

[sunby]

/ci-rerun-code-check

[sunby]

/ci-rerun-code-check
/ci-rerun-e2e-arm
/ci-rerun-e2e-default
/ci-rerun-go-sdk
/ci-rerun-integration-test
/ci-rerun-ut-go

[sunby]

/ci-rerun-code-check
/ci-rerun-e2e-arm
/ci-rerun-e2e-default
/ci-rerun-go-sdk
/ci-rerun-integration-test

[sunby]

/ci-rerun-code-check
/ci-rerun-e2e-arm
/ci-rerun-e2e-default
/ci-rerun-go-sdk
/ci-rerun-integration-test
/ci-rerun-ut-go

[sunby]

/ci-rerun-code-check
/ci-rerun-e2e-arm
/ci-rerun-e2e-default
/ci-rerun-go-sdk
/ci-rerun-integration-test

[sunby]

/ci-rerun-code-check
/ci-rerun-e2e-arm
/ci-rerun-e2e-default
/ci-rerun-go-sdk
/ci-rerun-integration-test
/ci-rerun-ut-go