[OC-1661] Removing inconsistent tooling configuration and changing gr…

[AlexGuironnetRTE]

Node and npm versions were not consistent depending on whether the build was launched using npm from the command line, a local gradle task or the CI build, which could have caused different behaviours/errors depending on the environment.
To fix this I:

• Updated the travis configuration to rely on the load_environment_light script that is used to set up local dev environments instead of separate configuration
• Removed the versions from the node plugin configuration in the ui gradle config.

In addition I took this opportunity to switch from the com.moowork.node plugin that doesn't seem to be maintained since early 2019 (see srs/gradle-node-plugin#315) to a community-maintained fork that looks more up-to-date (latest commit in February): https://github.com/node-gradle/gradle-node-plugin
Since it's a fork, I didn't need to make any changes to our existing configuration.

In release notes, under Tasks:

OC-1661: Removing inconsistent tooling configuration and changing gradle node plugin