fix: telemetry report error on windows

[zhongwencool]

Fixes https://emqx.atlassian.net/browse/EMQX-10938
os_mon is not included on windows, so the SysMemData = memsup:get_system_memory_data() always report error:
module could not be loaded.

Summary

🤖 Generated by Copilot at a2b06f4

Improved the reliability and portability of the emqx_telemetry application by using emqx_mgmt:vm_stats instead of memsup:get_system_memory_data to get the system memory. Added a test case to cover the scenario where os_mon is not available. Bumped the version number to 0.1.2.

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Added property-based tests for code which performs user input validation
• Changed lines covered in coverage report
• Change log has been added to changes/(ce|ee)/(feat|perf|fix)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• Created PR to emqx-docs if documentation update is required, or link to a follow-up jira ticket
• Schema changes are backward compatible

Checklist for CI (.github/workflows) changes

• If changed package build workflow, pass this action (manual trigger)
• Change log has been added to changes/ dir for user-facing artifacts update