RFR: 8366474: Rename MetaspaceObj::is_shared() to MetaspaceObj::in_aot_cache() [v2]

[Ioi Lam]

On Mon, 1 Sep 2025 06:58:15 GMT, David Holmes <dholmes at openjdk.org> wrote:

> Maybe the JBS title should be a bit more generic as you seem to be renaming many occurrences of "shared" not just the one listed.

The majority of the changes are about `is_shared` -> `in_aot_cache`. There are other changes like `_shared_metaspace_static_top` -> `_aot_metaspace_static_top`, but these are just implementation details.

This PR is one of the (many) subtasks for the "CDS" -> "AOT" renaming (main issue is [JDK-8366473](https://bugs.openjdk.org/browse/JDK-8366473)).  My plan is to name each subtask to indicate its main purpose. Otherwise it will be difficult to be both precise and concise in the JBS title. 
- I.e., in this step I renamed some "shared" but left others, so I can't precisely describe that without writing a long essay. 
- If I used a generic title then it's difficult to tell the difference with other subtasks.

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PR Comment: https://git.openjdk.org/jdk/pull/27016#issuecomment-3246575519