lsp: Do not drop lsp buffer handle from editor when a language change leads to buffer having a legit language (#44469)

Fixes a bug that led to us unnecessarily restarting a language server
when we were looking at a single file of a given language.

Release Notes:

- Fixed a bug that led to Zed sometimes starting an excessive amount of
language servers

crates/git_ui/src/file_diff_view.rs

@@ -108,7 +108,7 @@ impl FileDiffView {
         for buffer in [&old_buffer, &new_buffer] {
             cx.subscribe(buffer, move |this, _, event, _| match event {
                 language::BufferEvent::Edited
-                | language::BufferEvent::LanguageChanged
+                | language::BufferEvent::LanguageChanged(_)
                 | language::BufferEvent::Reparsed => {
                     this.buffer_changes_tx.send(()).ok();
                 }

crates/git_ui/src/text_diff_view.rs

@@ -170,7 +170,7 @@ impl TextDiffView {
 
         cx.subscribe(&source_buffer, move |this, _, event, _| match event {
             language::BufferEvent::Edited
-            | language::BufferEvent::LanguageChanged
+            | language::BufferEvent::LanguageChanged(_)
             | language::BufferEvent::Reparsed => {
                 this.buffer_changes_tx.send(()).ok();
             }