RFR: Update nmethod caching and clean up unused/duplicate methods [v8]

[Vladimir Kozlov]

On Thu, 12 Jun 2025 20:12:36 GMT, Ashutosh Mehra <asmehra at openjdk.org> wrote:

>> This PR updates nmethod caching to be based on caching of CodeBlob. It also cleans up some dead code and duplicate methods.
>
> Ashutosh Mehra has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add back CodeBuffer::clear_strings()
>   
>   Signed-off-by: Ashutosh Mehra <asmehra at redhat.com>

I submitted testing.

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PR Comment: https://git.openjdk.org/leyden/pull/71#issuecomment-2968216753