RFR: 8369692: JFR: Don't record thread metadata in case jdk.ThreadStart is disabled

[Kerem Kat]

On Mon, 10 Nov 2025 18:52:31 GMT, Kerem Kat <krk at openjdk.org> wrote:

> ### Before
> File size: 0.84 MB
> Scrubbed size: 0.82 MB
> Waste: 2.73%
> 
> ### After
> File size: 0.80 MB
> Scrubbed size: 0.78 MB
> Waste: 3.40%
> 
> File size decreases when `ThreadStart` and `ThreadEnd` events are disabled.

Thanks, closing in favor of JDK-8364258

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PR Comment: https://git.openjdk.org/jdk/pull/28222#issuecomment-3521745857