Always remove dropped tables from remote data folder cache

[CGodiksen]

This PR fixes a bug that causes errors if a table was dropped in a cluster and then a table with the same name was created. When we drop tables in clusters, the node receiving the DROP table statement is responsible for dropping the table from the remote data folder and its local data folder and each peer node is only responsible for dropping the table from their own local data folder.

However, since we cache the tables in both the local data folder and the remote data folder, and the cache is only cleared when the table is dropped from the DataFolder, the peer nodes never removed the cached version from their remote data folder. This means a cache error was caused on the peer nodes if a table with the same name was created again.

This PR moves cache removal up, adds a separate method for it in DataFolder, and always tries to remove the table from the remote data folder cache when it is dropped. This means we technically "remove" the table from the remote data folder cache twice on the node receiving the statement, but the operation is cheap.

[Copilot]

🟢 Approval recommended

The changes are localized, align with the stated cluster cache-invalidation bug, and reuse existing location computation to remove the correct cache entry.

Pull request overview

Fixes stale DeltaTable cache entries in clustered deployments so that dropping a table reliably invalidates cached remote-table handles on peer nodes, preventing cache-related errors when recreating a table with the same name.

Changes:

• Move Delta table cache invalidation out of delete_table_files() and make it an explicit step in DataFolder::drop_table().
• Add DataFolder::remove_delta_table_from_cache() to centralize cache invalidation logic.
• Ensure Context::drop_table() also clears the remote data folder cache (when present) to handle peer-node cache invalidation in clusters.

File summaries

File	Description
crates/modelardb_storage/src/data_folder/mod.rs	Refactors drop path to explicitly remove the dropped table’s DeltaTable from the cache via a new helper method.
crates/modelardb_server/src/context.rs	Clears the remote data folder’s cached DeltaTable on table drop to prevent stale cache usage on peer nodes in clusters.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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