Don't insert unnecessary space below the end of an inline transformation (#15865)

We achieved this by allowing block decorations to have a height of `0`
and superimposing the border on top of the line, as opposed to carving
out space below it.

Release Notes:

- N/A

---------

Co-authored-by: Jason <jason@zed.dev>

crates/assistant/src/inline_assistant.rs

@@ -334,7 +334,7 @@ impl InlineAssistant {
             BlockProperties {
                 style: BlockStyle::Sticky,
                 position: range.end,
-                height: 1,
+                height: 0,
                 render: Box::new(|cx| {
                     v_flex()
                         .h_full()