Don't override sticky scroll settings if intellisense is disabled, to avoid conflicts with Clangd

Environment

• OS and Version: Windows 10
• VS Code Version: 1.99.3
• C/C++ Extension Version: 1.25.3
• If using SSH remote, specify OS of remote machine: No SSH

Bug Summary and Steps to Reproduce

Refer to https://github.com/clangd/clangd/issues/2221

When both Clangd and the Micosoft's C/C++ extension are installed, the latter messes with the sticky scroll settings, prevending Clangd from displaying it properly.

This happens even with "C_Cpp.intelliSenseEngine": "disabled", which is probably undesirable.

I suggest disabling this behavior when intellisense is disabled.

How to repro:

• Install both the MS C/C++ extension and Clangd. Ensure Clangd is working.
• Disable intellisense when prompted (MS extension suggests this when it sees clangd).
• Trigger sticky scroll. Ensure that you follow the style where {s are on separate lines.
• Observe that the sticky scroll only displays the {s instead of the function signatures:

Configuration and Logs

Not relevant.

Other Extensions

No response

Additional context

No response

Reproduce the conflict with the Microsoft C/C++ extension and Clangd on Windows using the reported IntelliSense-disabled configuration, then trace the extension's sticky-scroll settings handling. Done means the C/C++ extension no longer overrides sticky-scroll behavior when IntelliSense is disabled, while normal IntelliSense behavior remains unchanged.