fix(cloud): parse HF ALLOW_HTTP the way object_store does

[jackylee-ch]

The Hugging Face store read ALLOW_HTTP as true only for true/1 (hf/mod.rs:390),
while object_store itself — and vortex-cloud's own property_as_bool for the OpenDAL stores
(opendal/mod.rs:213) — accept 1/true/on/yes/y case-insensitively. So ALLOW_HTTP=on,
which works for every other scheme, left HF requiring HTTPS and a plain-HTTP Hub endpoint
unreachable. #9782 aligned the OpenDAL side to object_store but left HF behind.

Fix

Pull the object_store boolean spellings into one parse_object_store_bool helper and route both
allow_http and property_as_bool through it, so the two cannot drift. property_as_bool's
behaviour (including the warn-on-non-boolean) is unchanged.

Tests

Adds HF cases in hf/tests.rs for the previously-rejected spellings; the on/yes/y cases
fail before the change and pass after. cargo test -p vortex-cloud --features hf, clippy, and
cargo +nightly fmt --check are clean.

AI assistance

Written with agentic AI assistance; I read all three boolean-parsing sites and reproduced the
on/yes rejection before and after.