[Testing] Add Memory Leak Test

[kurisu6912]

This pr add memory leak test, apache/tvm-ffi#327

Summary by CodeRabbit

• Tests
  • Added new memory-management and error-path tests to better detect garbage-collection and cyclic-reference issues.
  • Removed an older memory-capture test that duplicated coverage.
  • Removed a specific GEMM test and its helper routine to streamline the test suite; other GEMM tests remain.

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