env/windows-arm64/aws: delete

The Windows ARM64 builders on Azure have replaced the Windows ARM64
builders on AWS by now. Remove unused environment configuration; we
can bring it back or look it up in history if needed.

Updates golang/go#53541.
Updates golang/go#42604.
Updates golang/go#57408.

Change-Id: I080e4f5c53712c0470332a7d26d00c939136e57c
Reviewed-on: https://go-review.googlesource.com/c/build/+/462655
Run-TryBot: Dmitri Shuralyov <[email protected]>
Reviewed-by: Heschi Kreinick <[email protected]>
Reviewed-by: Carlos Amedee <[email protected]>
Reviewed-by: Than McIntosh <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: dmitshur