Add FastAlloc memory utilization trace.

[yao-xiao-github]

trace.127.0.0.1.4503.1633721886.QPQ6js.0.6.xml:<Event Severity="10" Time="1633727956.444388" DateTime="2021-10-08T21:19:16Z" Type="FastAllocMemoryUsage" ID="0000000000000000" TotalMemory="5635904" UnusedMemory="131072" Utilization="97.674339%" ThreadID="343995601335330077" Machine="127.0.0.1:4503" LogGroup="default" Roles="CC,CP,DD,GP,MS,RK,RV,SS,TL" />

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[foundationdb-ci]

AWS CodeBuild CI Report for macOS Catalina 10.15

• CodeBuild project: foundationdb-pull-request-build-macos
• Commit ID: 79a2332
• Result: SUCCEEDED
• Error: N/A
• Build Logs (available for 30 days)

[foundationdb-ci]

AWS CodeBuild CI Report for Linux CentOS 7

• CodeBuild project: foundationdb-pull-request-build
• Commit ID: 79a2332
• Result: SUCCEEDED
• Error: N/A
• Build Logs (available for 30 days)