Fix extra blank line at start of rendered reStructuredText code block
Fix a problem where the rendered HTML for reStructuredText code blocks includes an extra blank line at the start.
Because browsers present the content of <pre> elements exactly as written, there should be no newline after a <code> tag nested inside a <pre> tag.
Additionally, update the test's HTML equality comparison to not modify the content of <pre> elements. This ensures that the test considers whitespace and newline differences in the expected and the actual rendered HTML for preformatted text. Without this change, the tests pass erroneously.
The final commit updates the expected rendered HTML for the tests.
This MR addresses the extra blank line aspect of the following issues: