fix (docs) Render integartions inside highlight block (#15388)

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## Fix integrations wrapper visibility in code blocks with line
highlighting

### Problem
The integrations array wrapper (`integrations: [` and `],`) wasn't
showing/hiding correctly in the Vue quickstart and other guides that use
line highlighting syntax (e.g., `{3, 12-41}`).

### Root Cause
When code blocks have line highlighting, the `makeHighlightBlocks`
function wraps highlighted lines in `<HighlightBlock>` components. This
changed the DOM structure so that lines were no longer direct children
of the `<code>` element, but nested inside containers.

The runtime logic in `updateElementsVisibilityForOptions` assumed lines
were direct children, causing `allLines.indexOf(openLine)` to return
`-1` and breaking the wrapper show/hide logic.

### Solution
Added a `getAllCodeLines` helper function that properly traverses the
code block structure, extracting lines from both:
- Direct children (non-highlighted lines)
- Nested children inside HighlightBlock containers (highlighted lines)

This ensures the integrations wrapper visibility logic works correctly
regardless of whether the code block uses line highlighting.

### Files Changed
- `src/components/onboarding/index.tsx` - Added helper to handle nested
line structure in highlighted code blocks

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team](https://github.com/orgs/getsentry/teams/docs)

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---------

Co-authored-by: getsantry[bot] <66042841+getsantry[bot]@users.noreply.github.com>

Author: sergical

src/components/onboarding/index.tsx

@@ -239,7 +239,27 @@ export function updateElementsVisibilityForOptions(
     const codeBlock = openLine.closest('code.code-highlight');
     if (!codeBlock) return;
 
-    const allLines = Array.from(codeBlock.children) as HTMLElement[];
+    // Helper function to get all code lines, including those nested in HighlightBlocks
+    const getAllCodeLines = (container: Element): HTMLElement[] => {
+      const lines: HTMLElement[] = [];
+      Array.from(container.children).forEach(child => {
+        const el = child as HTMLElement;
+        // If it's a highlight-block, get lines from inside it
+        if (el.classList.contains('highlight-block')) {
+          // Lines are nested in highlight-block > div (CodeLinesContainer)
+          const linesContainer = el.querySelector('div');
+          if (linesContainer) {
+            lines.push(...(Array.from(linesContainer.children) as HTMLElement[]));
+          }
+        } else {
+          // Regular line, add it directly
+          lines.push(el);
+        }
+      });
+      return lines;
+    };
+
+    const allLines = getAllCodeLines(codeBlock);
     const openIndex = allLines.indexOf(openLine);
 
     // Find the matching close line in the same code block