Update build toolchain on 5.0.2 line

[basil]

• BOM maintenance requires that everything in the BOM have its build toolchain up-to-date at all times.
• junit must be in the BOM, as it is one of the most popular plugins.
• As long as junit is in the BOM, all of its current dependencies must be in the BOM.
• As long as Feature/UI tests junit-plugin#342 remains unaddressed, junit's current dependencies include bootstrap4-api and therefore echarts-api <= 5.0.2.
• As long as echarts-api <= 5.0.2 must remain in the BOM, its build toolchain must be kept up-to-date.

commit de25291 in this PR is based on top of echarts-api 5.0.2-1. It updates the build toolchain. I am asking that we backport these build toolchain updates to the 5.0.2 line and release 5.0.2-2. This would allow us to update the 5.0.2 version of echarts-api in the BOM, even without jenkinsci/junit-plugin#342, and unblock my other BOM work in the short term. For instructions on how to do a backport, see: https://gist.github.com/jglick/86a30894446ed38f918050c1180483e2

[uhafner]

I think spending time on a deprecated plugin is a waste of time. I therefore tried to fix the test cases of the JUnit plugin: jenkinsci/junit-plugin#272.

Then we can mark bootstrap4 plugin as deprecated.