svm: cache sysvar read lock per transaction batch

[atorrers]

Problem

TransactionBatchProcessor currently reads sysvar_cache inside execute_loaded_transaction for each transaction, which adds repeated RwLock read overhead on a hot execution path.

Summary of Changes

• Move sysvar_cache read to batch scope in load_and_execute_sanitized_transactions and reuse it across transactions.
• Pass &SysvarCache into execute_loaded_transaction instead of reading the lock inside that function.
• Update affected test call sites to pass the cached reference.
• Add #[allow(clippy::too_many_arguments)] on execute_loaded_transaction to satisfy CI clippy rules after adding the new parameter.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.0%. Comparing base (1518547) to head (ba31b6b).
⚠️ Report is 6 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #11604     +/-   ##
=========================================
- Coverage    83.0%    83.0%   -0.1%     
=========================================
  Files         850      850             
  Lines      322429   322437      +8     
=========================================
- Hits       267842   267807     -35     
- Misses      54587    54630     +43     

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