test: fix disabled test-fs-largefile

Add `common.refreshTmpDir()` before using the tmp directory.

fs.writeSync no longer requires an integer for the position argument, so
change test from `assert.throws()` to `assert.doesNotThrow()`. The test
now passes.

Because it involves a 5 GB file, we're not going to activate the test,
although that is possible if we add checking for appropriate available
resources (definitely disk space, likely memory, maybe check that it's a
64-bit OS).

PR-URL: https://github.com/nodejs/node/pull/13147


Reviewed-By: James M Snell <jasnell@gmail.com>