remove shared memory from precompiles and accept

[ceyonur]

Why this should be merged

Currently shared memory writes version DB to the shared database (avaDB). This conflicts and corrupts the standaloneDB and leads to a duality in data sources: acceptedBlockDB and metaDB were being written to the shared db (avaDB) and chaindb was being written to the standalone DB. This PR removes the unused shared memory components from subnet-evm.

How this works

This pull request includes significant refactoring and cleanup of the plugin/evm package, specifically focusing on the removal of shared memory operations and simplifying database interactions. The most important changes include the removal of the sharedMemoryWriter, modifications to the Accept method, and updates to the test cases to reflect these changes.

• plugin/evm/block.go: Removed the use of sharedMemoryWriter and related logic from the Accept method and handlePrecompileAccept function. [1] [2] [3]

• plugin/evm/shared_memory_writer.go: Deleted the entire shared_memory_writer.go file, which included the sharedMemoryWriter implementation.

• plugin/evm/vm.go: Modified the initializeDBs method to use avaDB directly instead of creating a versioned database.

• plugin/evm/vm_test.go: Updated test setup to use baseDB directly and added a new test TestStandaloneDB to ensure the standalone database is used correctly. [1] [2]

How this was tested

Added regression UT & locally tested

Need to be documented?

No

Need to update RELEASES.md?

No

[ARR4N]

I don't know enough about the problem to give a safe approval, but overall LGTM.