timeline: get rid of conversions from string to TimelineEventItemId

I suppose these were useful at the FFI layer at some point, but they
aren't anymore, so they could be removed.

Changelog: Got rid of `From<String/&str>` for `TimelineEventItemId`.

crates/matrix-sdk-ui/src/timeline/event_item/mod.rs

@@ -115,23 +115,6 @@ impl From<OwnedTransactionId> for TimelineEventItemId {
     }
 }
 
-// TODO remove those two
-impl From<String> for TimelineEventItemId {
-    fn from(value: String) -> Self {
-        value.as_str().into()
-    }
-}
-
-impl From<&str> for TimelineEventItemId {
-    fn from(value: &str) -> Self {
-        if let Ok(event_id) = EventId::parse(value) {
-            TimelineEventItemId::EventId(event_id)
-        } else {
-            TimelineEventItemId::TransactionId(value.into())
-        }
-    }
-}
-
 /// An handle that usually allows to perform an action on a timeline event.
 ///
 /// If the item represents a remote item, then the event id is usually
@@ -762,7 +745,7 @@ mod tests {
     };
 
     use super::{EventTimelineItem, Profile};
-    use crate::timeline::{TimelineDetails, TimelineEventItemId};
+    use crate::timeline::TimelineDetails;
 
     #[async_test]
     async fn test_latest_message_event_can_be_wrapped_as_a_timeline_item() {
@@ -987,20 +970,6 @@ mod tests {
         );
     }
 
-    #[test]
-    fn test_raw_event_id_into_timeline_event_item_id_gets_event_id() {
-        let raw_id = "$123:example.com";
-        let id: TimelineEventItemId = raw_id.into();
-        assert_matches!(id, TimelineEventItemId::EventId(_));
-    }
-
-    #[test]
-    fn test_raw_str_into_timeline_event_item_id_gets_transaction_id() {
-        let raw_id = "something something";
-        let id: TimelineEventItemId = raw_id.into();
-        assert_matches!(id, TimelineEventItemId::TransactionId(_));
-    }
-
     fn member_event(
         room_id: &RoomId,
         user_id: &UserId,