[BACKPORT][v1.6.1][BUG] potential risk to unmap a negative number

[github-actions]

backport #8235

[longhorn-io-github-bot]

Pre Ready-For-Testing Checklist

• Where is the reproduce steps/test steps documented?
  The reproduce steps/test steps are at:

Test plan:
Please refer the #8235 (comment) and following comments

* [ ] Is there a workaround for the issue? If so, where is it documented?
The workaround is at:

* [ ] Does the PR include the explanation for the fix or the feature?

* [ ] Does the PR include deployment change (YAML/Chart)? If so, where are the PRs for both YAML file and Chart?
The PR for the YAML change is at:
The PR for the chart change is at:

• Have the backend code been merged (Manager, Engine, Instance Manager, BackupStore etc) (including backport-needed/*)?
  The PR is at Prevent the unmap length of a negative number (backport #1064) longhorn-engine#1065

* [ ] Which areas/issues this PR might have potential impacts on?
Area
Issues

* [ ] If labeled: require/LEP Has the Longhorn Enhancement Proposal PR submitted?
The LEP PR is at

* [ ] If labeled: area/ui Has the UI issue filed or ready to be merged (including backport-needed/*)?
The UI issue/PR is at

* [ ] If labeled: require/doc Has the necessary document PR submitted or merged (including backport-needed/*)?
The documentation issue/PR is at

* [ ] If labeled: require/automation-e2e Has the end-to-end test plan been merged? Have QAs agreed on the automation test case? If only test case skeleton w/o implementation, have you created an implementation issue (including backport-needed/*)
The automation skeleton PR is at
The automation test case PR is at
The issue of automation test case implementation is at (please create by the template)

* [ ] If labeled: require/automation-engine Has the engine integration test been merged (including backport-needed/*)?
The engine automation PR is at

* [ ] If labeled: require/manual-test-plan Has the manual test plan been documented?
The updated manual test plan is at

* [ ] If the fix introduces the code for backward compatibility Has a separate issue been filed with the label release/obsolete-compatibility?
The compatibility issue is filed at

[innobead]

cc @longhorn/qa

[roger-ryao]

cc @longhorn/qa

After discussed with @Vicente-Cheng and he will look into whether there is a way to verify the issue without Harvester. If there is no way, he will build the Harvester ISOs for us to verify the issue around noon.

[roger-ryao]

Verified on v1.6.x-head 20240327

• Harvester version: 1.3.0
• longhorn v1.6.x-head 1cd64d6
• longhorn-engine v1.6.x-head longhorn/longhorn-engine@a7f8066

The test steps

#8235 (comment)

Result Passed

1. fstrim could be executed successfully.