Remove textDocument/diagnostic capability (#13102)

Edwin Aronsson created 

Zed currently does not support pull diagnostics, yet still has the
capability for it (`textDocument/diagnostic`) (added in
https://github.com/zed-industries/zed/commit/14993e087669c7103df2239a2628ee0d3ce38596).
Some language servers therefore assume Zed will use pull diagnostics,
which leads to there being no diagnostics at all. This PR removes this
capability, making it possible to get diagnostics with more language
servers.

Release Notes:

- N/A

Change summary

crates/lsp/src/lsp.rs | 4 ----
1 file changed, 4 deletions(-)

Detailed changes

crates/lsp/src/lsp.rs 🔗 

@@ -704,10 +704,6 @@ impl LanguageServer {
                     on_type_formatting: Some(DynamicRegistrationClientCapabilities {
                         dynamic_registration: None,
                     }),
-                    diagnostic: Some(DiagnosticClientCapabilities {
-                        related_document_support: Some(true),
-                        dynamic_registration: None,
-                    }),
                     ..Default::default()
                 }),
                 experimental: Some(json!({