RFR: Remove -XX:ContPerfTest

[Ron Pressler]

On Thu, 14 Oct 2021 14:09:46 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> When porting to x86_32, I noticed there is a diagnostic `ContPerfTest` option which effectively takes different paths, depending on diagnostic setting. Is it still useful? For a cleanup/preparation-for-upstreaming, I propose we roll it back.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug `jdk_loom hotspot_loom`

Done.

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PR: https://git.openjdk.java.net/loom/pull/76