Remove unnecessary app heap memory clean operations to reduce process RSS (#1608)
Remove unnecessary app heap memory clean operations to reduce process RSS (#1608)

With hardware boundary checking enabled, the app heap memory comes from `os_mmap()`.
Clearing the whole heap in the memory allocator causes process RSS to reach maximum
app heap size immediately and wastes lots of memory, so we had better remove the
unnecessary memory clean operations in the memory allocator.
bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime,bytecodealliance/wasm-micro-runtime