Run rspec system specs using Vue 3 when a label is set

What does this MR do and why?

This change creates a new "rspec system pg16 vue3" job that runs when the label pipeline:run-rspec-vue3 is set.

This change is a first step towards building compatibility with Vue 3.

References

• #562961
• Test pipeline with pipeline:run-rspec-vue3 at: !202209 (closed)

How to set up and validate locally

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