This implements the spec change in
https://github.com/tc39/ecma262/pull/2164

Making TA elements configurable has interaction with delete. While
the elements are configurable, they are only "deletable" via detaching
the underlying ArrayBuffer, not via `delete`. That is, `delete ta[idx]`
for an in-bounds `idx` still returns false.

Bug: v8:11281
Change-Id: I2e9348a7ec3c3239a92cc35e51b7182423736834
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2605234Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71955}