[Draft] Revert " [FFI] Re-introduce the boxed primitive values (#17257)"

[Lunderberg]

This reverts commit 02f48828e4b56995be0021c9a98e1705a837e712. The post-merge builds on main are failing in CI on both MacOS and Windows. The failure modes do not appear to be caused by the FFI changes, but the FFI changes impact enough parts of TVM that it's difficult to say that definitively.

[Lunderberg]

If the CI fails in the "CI / MacOS" and "CI / Windows" builds, that will indicate that the current build failures on main are unrelated to the changes in #17257.

[Lunderberg]

The CI for this PR fails with the same errors as seen on main (copied below), so the FFI changes are unrelated to the build failures. Closing this PR, as it is not necessary to revert the FFI changes.

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For the MacOS build:

conda.exceptions.CondaValueError: You have chosen a non-default solver backend (libmamba) but it was not recognized. Choose one of: classic

For the Windows build:

MSBUILD : error MSB1009: Project file does not exist.
Switch: install.vcxproj
cp: cannot stat 'C:\Miniconda\envs\tvm-build\conda-bld\tvm-package_1723485650581\_h_env\Library\lib\tvm.dll': No such file or directory
cp: cannot stat 'C:\Miniconda\envs\tvm-build\conda-bld\tvm-package_1723485650581\_h_env\Library\lib\tvm_runtime.dll': No such file or directory

BuildScriptException: Command '['C:\\Windows\\system32\\cmd.exe', '/d', '/c', 'C:\\Miniconda\\envs\\tvm-build\\conda-bld\\tvm-package_1723485650581\\work\\install_libtvm.bat']' returned non-zero exit status 1.