Silence warnings in scripts/rspec_check_order_dependence

What does this MR do and why?

This MR silences warnings for missing feature category (Missing metadata feature_category:) in scripts/rspec_check_order_dependence so the output is readable.

How to set up and validate locally

scripts/rspec_check_order_dependence spec/policies/group_policy_spec.rb
+ export RSPEC_WARN_MISSING_FEATURE_CATEGORY=0
+ RSPEC_WARN_MISSING_FEATURE_CATEGORY=0
+ bin/rspec --order defined --format progress spec/policies/group_policy_spec
Run options: include {:focus=>true}

All examples were filtered out; ignoring {:focus=>true}

Test environment set up in 5.129303031 seconds
.....

master

$ scripts/rspec_check_order_dependence spec/policies/group_policy_spec.rb
+ bin/rspec --order defined --format progress spec/policies/group_policy_spec.rb
Run options: include {:focus=>true}

All examples were filtered out; ignoring {:focus=>true}

Test environment set up in 5.247225441 seconds
Missing metadata feature_category: ./spec/policies/group_policy_spec.rb:13 See https://docs.gitlab.com/ee/development/testing_guide/best_practices.html#feature-category-metadata
.Missing metadata feature_category: ./spec/policies/group_policy_spec.rb:28 See https://docs.gitlab.com/ee/development/testing_guide/best_practices.html#feature-category-metadata
.Missing metadata feature_category: ./spec/policies/group_policy_spec.rb:47 See https://docs.gitlab.com/ee/development/testing_guide/best_practices.html#feature-category-metadata
.
RSpec is shutting down and will print the summary report... Interrupt again to force quit.
Missing metadata feature_category: ./spec/policies/group_policy_spec.rb:62 See https://docs.gitlab.com/ee/development/testing_guide/best_practices.html#feature-category-metadata

MR acceptance checklist

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