fix(router): don't fail on route with multiple paths

[hanshuebner]

Summary

In traditional_compatible mode, the router would fail to work if a route with multiple paths but no service would be created.

Checklist

• The Pull Request has tests
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fixes KAG-1961

[gszr]

Does it need a backport to older than 3.3?

[team-gateway-bot]

The backport to release/3.3.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-release/3.3.x release/3.3.x
# Navigate to the new working tree
cd .worktrees/backport-release/3.3.x
# Create a new branch
git switch --create backport-11158-to-release/3.3.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 b0bd002f3f573b5eff821ff6cf85278defc2df21
# Push it to GitHub
git push --set-upstream origin backport-11158-to-release/3.3.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-release/3.3.x

Then, create a pull request where the base branch is release/3.3.x and the compare/head branch is backport-11158-to-release/3.3.x.

[hanshuebner]

Does it need a backport to older than 3.3?

No, the change that caused this issue was introduced in 3.3.