The `FunctionTemplate::SetHiddenPrototype()` API was deprecated
beginning of the year and all uses in Node.js and Chrome have been
removed appropriately. This removes the implementation of the method
and the bit in the `FunctionTemplateInfo`, but retains the bit in
the Map for now. That will be cleaned up as a second step later.

Bug: v8:9183, v8:9267
Change-Id: I9aa2fc484b3321f4f42a29a0a38d72a6d30054a7
Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1627329
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61771}