Revert "Start diagnostic group_id at 1 to handle non LS diagnostics (#22694) (#22700)

This reverts commit 3ae6aa0e4d.

If "group_id = 0" really did mean a diagnostic not from a language
server then various methods related to diagnostic set would need to be
updated. Something like [this
diff](https://gist.github.com/mgsloan/e902153bcaec207b39260a8f40d3134d).

Plan instead is to use InfoPopover instead of DiagnosticPopover for
these.

Release Notes:

- N/A

crates/project/src/lsp_store.rs

@@ -2960,7 +2960,7 @@ impl LspStore {
                 http_client,
                 fs,
                 yarn,
-                next_diagnostic_group_id: 1,
+                next_diagnostic_group_id: Default::default(),
                 diagnostics: Default::default(),
                 _subscription: cx.on_app_quit(|this, cx| {
                     this.as_local_mut().unwrap().shutdown_language_servers(cx)