Fix flaky tests in base_spec file

Related to #448513 (closed)

What does this MR do?

• Fixes the flaky tests in spec/requests/api/internal/base_spec.rb

Why?

• There were unnecessary leftover expectations from this old rate_limit_gitlab_shell_by_ip feature flag.

How to set up and validate locally

1. Before cloning this branch, run the following commands on the master branch to verify flakiness:

bin/rspec ./spec/requests/api/internal/base_spec.rb` -fd 

Past seeds from flaky jobs

bin/rspec ./spec/requests/api/internal/base_spec.rb -fd --seed 63433

bin/rspec ./spec/requests/api/internal/base_spec.rb -fd --seed 11345

3. Clone this branch
4. Repeat step 1 to make sure the tests pass

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