Add missing YARD annotation to devfile parser

What does this MR do and why?

Add missing YARD annotation to devfile parser which was missed in Add workspace domain as environment variable (!123907 - merged)

See Add Yard method annotation for Remote Dev servi... (!124546 - merged) for details on why/how we are using YARD in the Remote Development feature.

We will look into enforcing these through some LEFTHOOK or CI rules, or possibly scripts/remote_development/run-smoke-test-suite.sh (or perhaps deleting them if they don't provide enough value for the maintenance effort), but for now they only show up as warnings when running RubyMine Inspect Code.

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