[Data] Remove dead ESTIMATED_SAFE_MEMORY_FRACTION constant (ray-proje…

…ct#44957)

ESTIMATED_SAFE_MEMORY_FRACTION isn't used anywhere, so this PR removes it (it's been superseded by ResourceManager.DEFAULT_OBJECT_STORE_MEMORY_LIMIT_FRACTION).

Signed-off-by: Balaji Veeramani <balaji@anyscale.com>

python/ray/data/context.py

@@ -14,9 +14,6 @@
 _default_context: "Optional[DataContext]" = None
 _context_lock = threading.Lock()
 
-# An estimate of what fraction of the object store a Dataset can use without too high
-# a risk of triggering spilling. This is used to generate user warnings only.
-ESTIMATED_SAFE_MEMORY_FRACTION = 0.25
 
 # We chose 128MiB for default: With streaming execution and num_cpus many concurrent
 # tasks, the memory footprint will be about 2 * num_cpus * target_max_block_size ~= RAM