fix(ruby-yoshi): Remove bolded scope and fix link removal

[dazuma]

Two more minor adjustments to the changelog formatting for ruby-yoshi.

• Because we have monorepos, we typically include the package name in the scope of the commit message so we can identify commits in the history more easily. But the package name isn't useful in the changelog since each package has is own changelog, so we're removing it.
• Adjusted the regex that removes trailing links to pull requests and commits, so it will handle any number of such links in any order (the previous regex did not recognize a commit link that didn't follow a pr link) and to limit it to github links to reduce false positives.