Fix debouncing issue in vscode autocomplete

[JakeDawkins]

This is an incremental improvement to the autocomplete handling in the language server. this is not a 100% fix for all of the issues in autocomplete but hopefully is a complete fix for the ctrl+space recommendations in vscode.

Ctrl+space and autocomplete right now doesn't work properly. The recommended options are showing the fields for the parent type.

This is because of the leading: false option being passed to the debounce function. In addition, this PR reduces the debounce timeout to make other issues with autocomplete less obvious

TODO:

• Update CHANGELOG.md* with your change (include reference to issue & this PR)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass

*Make sure changelog entries note which project(s) has been affected. See older entries for examples on what this looks like.