[release tool]: run nvm gracefully to ensure caretaker uses correct node version for publish branch

The merge tool will currently check out other branches, such as patch, LTS etc. For that the node versions could be different and breaking. This currently results in some inconvenient Yarn install engines error mid-publishing in a way where recovering is rather cumbersome..

We should run `nvm` automatically, gracefully as not everbody might have it. If it fails, we print a warning and proceed running the Yarn install. That one could still fail in such cases, but this is expected then.

Note: We have considered using the Bazel-managed Node version (that would be ideal).. but we cannot let Bazel install the node modules as Bazel itself is actually made available through the `@bazel/bazelisk` package (caretaker might not have the proper Bazel version globally installed; if at all)

Comienza por el flujo de branch-checkout e instalación de Yarn de la herramienta de merge, especialmente donde la publicación cambia a ramas patch o LTS. Comprueba cómo gestiona actualmente la herramienta la configuración del entorno y verifica después que nvm se intente de forma controlada, que se muestren advertencias cuando no esté disponible o falle, y que Yarn install continúe ejecutándose.

Escrito por el modelo de indexación a partir del texto del issue.