starlark_lsp: remove all completion triggers

Summary:
D53530861 removed a few completion triggers that were uncontroversial, and this improved the appearance of annoying autocomplete popups.
This diff removes the rest of the trigger characters, because after further testing they aren't very useful:

opening parenthesis:
{F1456353169}

string quote:
{F1456353307}

assignment doesn't seem to work anyway.

Reviewed By: JakobDegen

Differential Revision: D53756130

fbshipit-source-id: 8bc9ef96158f9320d37f8382406de298099e5f0a

starlark-rust/starlark_lsp/src/server.rs

@@ -47,7 +47,6 @@ use lsp_types::request::GotoDefinition;
 use lsp_types::request::HoverRequest;
 use lsp_types::CompletionItem;
 use lsp_types::CompletionItemKind;
-use lsp_types::CompletionOptions;
 use lsp_types::CompletionParams;
 use lsp_types::CompletionResponse;
 use lsp_types::DefinitionOptions;
@@ -406,17 +405,6 @@ impl<T: LspContext> Backend<T> {
         ServerCapabilities {
             text_document_sync: Some(TextDocumentSyncCapability::Kind(TextDocumentSyncKind::FULL)),
             definition_provider,
-            completion_provider: Some(CompletionOptions {
-                trigger_characters: Some(vec![
-                    // e.g. function call
-                    "(".to_owned(),
-                    // e.g. variable assignment
-                    "=".to_owned(),
-                    // e.g. string literal (load path, target name)
-                    "\"".to_owned(),
-                ]),
-                ..Default::default()
-            }),
             hover_provider: Some(HoverProviderCapability::Simple(true)),
             ..ServerCapabilities::default()
         }