Autocomplete: re-enable agent tests

[valerybugakov]

• No functional changes.
• 90% of the diff are recordings and bindings updates 🙂
• Re-enabled existing autocomplete integration tests and improved the stability of recoding updates. Initially, they were disabled here: Agent: update access token for integration tests #5629
• Replaced most of the sleep calls with new agent testing/X requests to await for a timeout in question (Slack thread).
• Removed the NoopCompletionItemProvider registration for unauthenticated users to fix the flaky behavior where the real autocomplete provider was not registered before the first autocomplete/execute call in tests (Slack thread). Autocomplete is currently available only for authenticated requests, so this change should not have any functional side effects.
• Updated Kotlin bindings (some are not related to this PR, but AFAIK, this is caused by the main branch not being updated).
• Part of https://linear.app/sourcegraph/issue/CODY-3910/add-autocomplete-integation-tests-for-server-side-model-config

Test plan

CI and pnpm vitest agent/src/autocomplete.test.ts

[sqs]

Very nice, great to get these enabled again. Thanks!