tests.system.vertexai.test_tokenization.TestTokenization: many tests failed

Many tests failed at the same time in this package.

* I will close this issue when there are no more failures in this package _and_
there is at least one pass.
* No new issues will be filed for this package until this issue is closed.
* If there are already issues for individual test cases, I will close them when
the corresponding test passes. You can close them earlier, if you prefer, and
I won't reopen them while this issue is still open.

Here are the tests that failed:
* test_count_tokens_local[_get_tokenizer_for_model_preview-gemini-1.5-pro-002-udhr-udhr-PROD_ENDPOINT] (#4624)
* test_count_tokens_local[get_tokenizer_for_model-gemini-1.5-pro-002-udhr-udhr-PROD_ENDPOINT]
* test_compute_tokens[_get_tokenizer_for_model_preview-gemini-1.5-pro-002-udhr-udhr-PROD_ENDPOINT]
* test_compute_tokens[get_tokenizer_for_model-gemini-1.5-pro-002-udhr-udhr-PROD_ENDPOINT] (#4625)
* test_count_tokens_system_instruction[gemini-1.5-pro-002-PROD_ENDPOINT]
* test_count_tokens_system_instruction_is_function_call[gemini-1.5-pro-002-PROD_ENDPOINT]
* test_count_tokens_system_instruction_is_function_response[gemini-1.5-pro-002-PROD_ENDPOINT]
* test_count_tokens_tool_is_function_declaration[gemini-1.5-pro-002-PROD_ENDPOINT]
* test_count_tokens_content_is_function_call[gemini-1.5-pro-002-PROD_ENDPOINT]
* test_count_tokens_content_is_function_response[gemini-1.5-pro-002-PROD_ENDPOINT]

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commit: ac5a5e4dd07890d07a553218d42040a6136fbb41
buildURL: [Build Status](https://source.cloud.google.com/results/invocations/0826b007-d9af-4e60-8584-d03c9cac927a), [Sponge](http://sponge2/0826b007-d9af-4e60-8584-d03c9cac927a)
status: failed