Remove around(:context) warning when running specs

What does this MR do?

Remove around(:all) warning when running specs

$ bundle exec spring rspec ee/spec/features/groups/saml_providers_spec.rb:188

WARNING: `around(:context)` hooks are not supported and behave like `around(:example). Called from /Users/tanle/Code/gitlab/gitlab-development-kit/gitlab/spec/support/omniauth_strategy.rb:36:in `block in <main>'.

WARNING: `around(:context)` hooks are not supported and behave like `around(:example). Called from /Users/tanle/Code/gitlab/gitlab-development-kit/gitlab/ee/spec/features/groups/saml_providers_spec.rb:18:in `block in <main>'.

around(:all) is not supported by rspec_core and will be removed in future release.

Related upstream change https://github.com/rspec/rspec-core/pull/2687

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