Fix SQL mode showing each table entry twice

[alex-fedotyev]

Type of Change

Please check the relevant option.

• 🚀 Feature
• 🐛 Bug Fix
• 📝 Documentation
• 🧹 Refactor / Chore

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Bug Fix

What is the bug?

In SQL mode, each table entry appears twice (or more) in the autocomplete suggestions. registerSQL() in sqlProvider.ts calls monaco.languages.registerCompletionItemProvider() and registerDocumentFormattingEditProvider() every time the SQL editor mounts, but never disposes of the previous registrations. Since Monaco stacks providers rather than replacing them, each editor remount (e.g. switching between Builder and SQL mode, or navigating between panels) adds another provider returning the same suggestions, causing duplicate table entries that multiply with each remount.

How to reproduce

1. Open a ClickHouse datasource query editor and switch to SQL mode
2. Start typing a FROM clause to trigger table autocomplete — observe suggestions
3. Switch to Builder mode, then back to SQL mode
4. Trigger table autocomplete again — each table now appears twice
5. Repeat switching — duplicates multiply with each remount

Related Issues

Closes HDX-3957

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Please check that:

• Tests for this change have been added/updated.
• Documentation has been added/updated (where applicable).

Special notes for your reviewer

This is a minimal, targeted fix. The root cause is that Monaco's registerCompletionItemProvider and registerDocumentFormattingEditProvider return IDisposable objects that must be disposed to remove the provider. Without disposal, providers accumulate and each one independently returns the full set of suggestions, leading to duplicates.

registerSQL() now returns an SQLRegistration object that captures both disposables and exposes a dispose() method. SqlEditor stores this in a ref and calls dispose() in onEditorWillUnmount.

All 64 existing test suites (592 tests) continue to pass.

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