Report title formatted incorrectly with short description in build summary #644

Describe the bug

When using build summary output with a report title, the output is not formatted correctly (see screenshot). Note how the short summary appears before the title, and the '#' indicating Heading 1 also appears in the text.

To Reproduce

Steps to reproduce the behavior:

1. In the action configuration, set report-title to a non-empty string.
2. Run a build.
3. Click on the Summary tab.
4. Observe the error.

Expected behavior

The report title should appear before the short summary, or else replace it entirely.

Screenshots

This is the observed behavior when report-title is set to "Test Results".

Raw Markdown:

# 250 passed, 0 failed and 1 skipped # Test Results
![Tests passed successfully](https://img.shields.io/badge/tests-250%20passed%2C%201%20skipped-success)

Additional context

It seems that when the short summary was added in #589, it was done without regard to the presence of a report title.