Unpin aosp builds from C++17 As Yuxin pointed out upstream libcxx was updated so we shouldn't need to pin in Android any more. We still can't have C++20 code in ANGLE due to Skia, so some of (Chromium CI) bots will continue building as C++17. Bug: angleproject:330910097 Change-Id: I41a9a1f727ae47ccb450853b8a5ed0f0f5edd26d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6309328 Reviewed-by: Yuxin Hu <yuxinhu@google.com>