Reduce default 'large array' threshold
As-is this threshold is `512kb`, but as #9449 points out this is way too high for most people to consider sensible (why would you want to copy `256kb` of data around on the stack or duplicate it via `const`) and didn't get any discussion when originally added. This PR reduces it the threshold to `1kb`, which is higher than the issue says ("a few cpu words") but helps out for actual codebases.
While reducing this, I found that `large_stack_arrays` was triggering for statically promoted arrays in constants/statics, so I also fixed that up as seen in the difference to [array_size_threshold.stderr](https://github.com/rust-lang/rust-clippy/compare/master...GnomedDev:rust-clippy:reduce-large-threshold?expand=1#diff-4c2a2a855d9ff7777f1d385be0c1bede2a3fc8aaab94837cde27a35235233fc7).
Closes#9449.
changelog: [`large_stack_arrays`]: No longer triggers in `static`/`const` context
changelog: [`large_const_arrays`]: Changed the default of [`array-size-threshold`] from `512kb` to `16kb`
2d2e8cc21f