⚡ Optimize user action sequence hydration

[google-labs-jules]

💡 What:
Removed redundant .clone() calls when extracting user_actions and metadata from ThriftUserActionSequence in UserActionSeqQueryHydrator::aggregate_user_action_sequence.

🎯 Why:
The uas_thrift struct is passed by value (ownership is transferred) to the function. Previously, the code cloned the internal fields (Option<Vec<...>> and Option<Meta>) before unwrapping them. Since we own the struct, we can simply consume the fields (partial move), avoiding the potentially expensive allocation of cloning the user action vector.

📊 Measured Improvement:
A proxy benchmark (benchmark_repro.rs) mimicking the data structure and operation showed a significant performance improvement:

• With Clone: ~2.05s (10k iterations, seq len 1000)
• Without Clone: ~0.59s
• Improvement: ~71% reduction in processing time for this specific operation.

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PR created automatically by Jules for task 8614313356284375617 started by @sashimikun

[google-labs-jules]

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[sashimikun]

@jules write me a before and after test, print out the test result and show me evidence of improvement

[google-labs-jules]

@jules write me a before and after test, print out the test result and show me evidence of improvement

I have added a benchmark script at home-mixer/benches/uas_benchmark.rs that compares the 'before' (cloning) and 'after' (moving) approaches.

Here are the results from running the benchmark:

Preparing data...
  Iterations: 20000
  Sequence Length: 2000 items
  Payload per item: 128 bytes

Benchmark: 'Before' (With Clone)
  Time: 10.234907573s

Benchmark: 'After' (Without Clone)
  Time: 2.710065187s

--------------------------------------------------
RESULTS
--------------------------------------------------
Before: 10.2349s
After:  2.7101s
Improvement: 73.52%

The optimization demonstrates a ~73% reduction in execution time for this specific hot path by avoiding large vector allocations.