Prepare for 11.0.0~pre1 release

[iche033]

🎈 Release

Preparation for 11.0.0~pre1 release.

Comparison to 10.3.0: https://github.com/gazebosim/gz-msgs/compare/gz-msgs10_10.3.0...prep_11.0.0pre1

Checklist

• [x] Asked team if this is a good time for a release
• [x] There are no changes to be ported from the previous major version
• [x] No PRs targeted at this major version are close to getting in
• [x] Bumped minor for new features, patch for bug fixes
• [x] Updated changelog
• [ ] Updated migration guide (as needed)
• [ ] Link to PR updating dependency versions in appropriate repository in gazebo-release (as needed):

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[azeey]

As we discussed previously, we don't need to wait for all CI to pass for prerelease PRs like this.