DEV: Use use_redis_snapshotting in rate limiting test (#22270)

Why is this change required?

Prevents the test from leaking state in Redis and ends up causing other
tests to become flaky.

spec/lib/auth/default_current_user_provider_spec.rb

@@ -202,6 +202,8 @@ RSpec.describe Auth::DefaultCurrentUserProvider do
     context "with rate limiting" do
       before { RateLimiter.enable }
 
+      use_redis_snapshotting
+
       it "rate limits admin api requests" do
         global_setting :max_admin_api_reqs_per_minute, 3