This is a follow on from WT-14040. Motivating comment thread is here.

The live restore code checks if the thread already owns the lock via a

bool reentrant = __wt_spin_owned(session, &lr_fs->state_lock);

call, however other areas of the code base pass a `locked` argument into the function. We should review whether we can pass a `locked` flag into the functions instead of using the reentrant check.

If this is possible we could also look at chaning the state_lock from a spinlock to a read-write lock, as this will allow concurrent read accesses for a small speed boost.