The metadata-regen job runs inside the px4io/px4-dev container which
has no Node.js. The actions/setup-node action only installs on the
host runner, not inside the container, causing yarn: not found errors.
Replace actions/setup-node with direct Node.js installation via
NodeSource and enable corepack for Yarn support.
Signed-off-by: Ramon Roche <mrpollo@gmail.com>