Remove assertion about history items

For unknown reasons this assertion fails.  This means that 1b9b893169 (After
reading corrupted history entry, keep reading older entries, 2024-10-06)
is not fully working.  Go back to historical behavior for now.

Closes #11236

(cherry picked from commit 4f80e5cb54)

src/history/file.rs

@@ -369,7 +369,9 @@ fn extract_prefix_and_unescape_yaml(line: &[u8]) -> Option<(Cow<[u8]>, Cow<[u8]>
 fn decode_item_fish_2_0(mut data: &[u8]) -> Option<HistoryItem> {
     let (advance, line) = read_line(data);
     let line = trim_start(line);
-    assert!(line.starts_with(b"- cmd"));
+    if !line.starts_with(b"- cmd") {
+        return None;
+    }
 
     let (_key, value) = extract_prefix_and_unescape_yaml(line)?;