RFR: 8371681: Remove unused VMOp type CollectForCodeCacheAllocation

[Albert Mingkun Yang]

On Wed, 12 Nov 2025 07:40:56 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> The VMOp type `CollectForCodeCacheAllocation` was added with [JDK-8284161](https://bugs.openjdk.org/browse/JDK-8284161) but was never used. More than likely this is some vestigial part from earlier iterations of the Loom project.
> 
> I suggest a trivial removal of this unused symbol.
> 
> * Testing
>    * GHA

Marked as reviewed by ayang (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/28256#pullrequestreview-3452841467