Migrate more events to telemetry::event! macro (#24102)

I believe this takes care of the remaining events running through the
old flow that requires transformation at the collab server level. I
think all events are now going through `telemetry::event!()`.

For anyone curious where the new telemetry names are coming from, you
can check the `for_snowflake` function within
`crates/collab/src/api/events.rs`, to see how collab is currently
transforming the events going through the old flow.

Release Notes:

- N/A

crates/markdown_preview/src/markdown_preview_view.rs

@@ -497,7 +497,7 @@ impl Item for MarkdownPreviewView {
     }
 
     fn telemetry_event_text(&self) -> Option<&'static str> {
-        Some("markdown preview")
+        Some("Markdown Preview Opened")
     }
 
     fn to_item_events(_event: &Self::Event, _f: impl FnMut(workspace::item::ItemEvent)) {}