Disable DCA and writing diagnostics on did_change events

[JoshuaBatty]

Description

This PR does 3 optimizations. The timings below are measured against the LSP benchmarking project.

1. Disable running DCA & control flow analysis, for didChange events 39.544ms
2. Disable running collect_types_metadata for didChange events 3.522ms
3. Only write the diagnostics res to self.diagnostics.write() on didSave 21.135ms

I also had to increase the frequency that we are calling GC to every 3rd keystroke as during stress tests I was occasionally getting stack overflows otherwise.

related to #5445

Checklist

• [x] I have linked to any relevant issues.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have updated the documentation where relevant (API docs, the reference, and the Sway book).
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• [ ] I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• [ ] I have requested a review from the relevant team or maintainers.