fix test for RotaryEmbedding

[fs-eire]

Description

the BaseTester::Run function signature is:

void BaseTester::Run(ExpectResult expect_result, const std::string& expected_failure_string,
                     const std::unordered_set<std::string>& excluded_provider_types,
                     const RunOptions* run_options,
                     std::vector<std::unique_ptr<IExecutionProvider>>* execution_providers,
                     ExecutionMode execution_mode,
                     const Graph::ResolveOptions& options);

Its behavior is:

• if the parameter execution_providers is empty, it will try to aggregate all execution providers available in the build, and for each EP, create inference session and perform test.
• if the parameter execution_providers is not empty, it will run a single inference session, use the passed-in execution_providers as session options and perform test.

The old code may put multiple EPs into single inference sessions, but at runtime there will be only one EP running the test. Specifically, WebGPU EP is after CPU EP in this case, so the test never run on WebGPU EP.

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