Description:

The TestThrottleRetryAfter test was intermittently failing on CI due to timing and scheduling issues. Previously, it relied on blocking, sleeps, and sequential request batches, making results non-deterministic.

Problem:

• Tokens could be released before the next batch of requests was issued, causing expected 429 responses to be missed.
• The test was overly complex and prone to intermittent failures.

Solution:

• Removed sequential batches and blocking.
• Dispatched all requests concurrently to a handler with a small processing delay.
• Only validates total number of successful (200 OK) and throttled (429 Too Many Requests) requests matches the configured limit.
• Retry-After header is correctly set in throttled responses.

Result:

• Test is simpler, faster, and reliable on CI.
• No longer depends on the execution order of goroutines or sequential sleeps to enforce token consumption.
• Accurately verifies that the throttler enforces the request limit and sets the Retry-After header correctly.

#608