[Enhancement] Add system memory metrics for fe

[Dam1029]

Proposed changes

Currently, fe's SystemMetrics only support tcp. I add system memory metrics for fe. Then we can get system memory metrics , which is used to troubleshoot memory problems.

Types of changes

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• [] Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• [] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)
• [] Code refactor (Modify the code structure, format the code, etc...)

Checklist

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• [] I have create an issue on (Fix #ISSUE), and have described the bug/feature there in detail
• Compiling and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• If this change need a document change, I have updated the document
• Any dependent changes have been merged

Further comments

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[morningman]

LGTM

[morningman]

Hi @Dam1029 please resolve the conflict

[Dam1029]

Hi @Dam1029 please resolve the conflict

ok. I have resolved the conflict.

[morningman]

LGTM