Fix inline assist deletion blocks (#15651)

After the changes in #15536, block decorations need to be given an
explicit height if their content doesn't consume height on its own. We
missed that inline transformation deletion decorations didn't do this,
creating weird results. This fixes the issue and prevents block
decorations from ever having a zero height. That helps avoid major
weirdness, but this still a bit of a gotcha.

We need to back port this to Preview Channel (0.147.x)

Release Notes:

- N/A

---------

Co-authored-by: Antonio <antonio@zed.dev>

crates/assistant/src/inline_assistant.rs

@@ -1015,6 +1015,7 @@ impl InlineAssistant {
                         div()
                             .bg(cx.theme().status().deleted_background)
                             .size_full()
+                            .h(height as f32 * cx.line_height())
                             .pl(cx.gutter_dimensions.full_width())
                             .child(deleted_lines_editor.clone())
                             .into_any_element()