Am improve danger suggestion for feature category

What does this MR do and why?

Describe in detail what your merge request does and why.

Related #385306 (closed)

Add suggestions for feature_category only when we have a changed line of a top-level Rspec.describe block with a do at the end.

Like: RSpec.describe Tooling::Danger::ConfigFiles do

This means that in cases like next one we will not add a suggestion.

RSpec.describe BulkImports::CreateService,
:importers do

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