[core] Deflake `windows://python/ray/tests:test_get_locations` by reducing object size

[rynewang]

In the test failure CI, I find this log:

(raylet) [2024-05-12 02:51:50,631 C 11560 2720] (raylet.exe) dlmalloc.cc:129: Check failed: *handle != nullptr CreateFileMapping() failed. GetLastError() = 1450

So maybe it's using too much mem and windows got OOM. Reducing the object size in CI.

Fixes https://github.com/ray-project/ray/issues/45278

[rynewang]

@jjyao windows test passed, let's merge this and deflake