RFR: 8351142: Add JFR monitor deflation and statistics events [v3]

[Aleksey Shipilev]

On Fri, 7 Mar 2025 13:28:43 GMT, Erik Gahlin <egahlin at openjdk.org> wrote:

> I'm hesitant because the peak value can easily be calculated, which we already do for other events (CPULoad, NetworkUtilization, NativeMemoryUsage etc) in "jfr view".

True, I thought about that, and still ended up adding `max`, because it is tracked internally by locking subsystem, and thus does not run into sampling bias. I.e. JFR sampling thread may not see the spike in monitor counts if bulk inflation/deflation happens between two samples.

Looking around other stats in the `metadata.xml`, maybe a better name for it is `peakCount`?

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PR Comment: https://git.openjdk.org/jdk/pull/23900#issuecomment-2710038641