Simplify TryGetAbsoluteIndex check by using result directly in if condition

Changed from storing the result in endSync variable and checking it separately
to directly using the TryGetAbsoluteIndex result in the if condition with
negation. This makes the code more concise and easier to read.

Co-authored-by: ToddGrun <[email protected]>

Author: Copilot

src/Razor/src/Microsoft.CodeAnalysis.Razor.Workspaces/DocumentMapping/AbstractDocumentMappingService.cs

@@ -108,8 +108,7 @@ public IEnumerable<TextChange> GetRazorDocumentEdits(RazorCSharpDocument csharpD
                 // gave us, and see if we can map that.
 
                 // Get the end of the start line
-                var endSync = csharpSourceText.TryGetAbsoluteIndex(startLine, csharpSourceText.Lines[startLine].Span.Length, out var endIndex);
-                if (endSync is false)
+                if (!csharpSourceText.TryGetAbsoluteIndex(startLine, csharpSourceText.Lines[startLine].Span.Length, out var endIndex))
                 {
                     break;
                 }