[jdk25u-dev] RFR: 8362573: Incorrect weight of the first ObjectAllocationSample JFR event (regression)

[Vishal Chand]

Backport of:

* 8362573: Incorrect weight of the first ObjectAllocationSample JFR event (regression)
* Fixes the incorrect weight reported for the first ObjectAllocationSample JFR event by ensuring that allocations that occurred before the recording start are not counted in the event weight.

Testing
* New test passes with the fix and fails without the fix.

Low risk as this is a clean backport.

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Commit messages:
 - Backport b19e872192106f47c5d9b425230cc2bfe3e4786c

Changes: https://git.openjdk.org/jdk25u-dev/pull/29/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk25u-dev&pr=29&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8362573
  Stats: 177 lines in 7 files changed: 116 ins; 30 del; 31 mod
  Patch: https://git.openjdk.org/jdk25u-dev/pull/29.diff
  Fetch: git fetch https://git.openjdk.org/jdk25u-dev.git pull/29/head:pull/29

PR: https://git.openjdk.org/jdk25u-dev/pull/29