fix: remove unnecessary LSAN suppressions for Arrow S3

FinalizeS3() is now properly called via GTest Environment teardown,
so S3 global state is cleaned up correctly.  The leak suppressions
are no longer needed.

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Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

.github/lsan-suppressions.txt

@@ -19,8 +19,3 @@
 # Format:
 # leak:SymbolName
 # leak:source_file.cc
-
-# Arrow S3 initialization allocates global state that is intentionally not freed
-# because FinalizeS3() cannot be safely called during static destruction.
-leak:arrow::fs::InitializeS3
-leak:Aws::