cmd/{apidiff,gorelease}: delete redundant //go:debug gotypesalias=1 directives [generated]

The module's go directive is >= 1.23 now,
so these files no longer have any effect.

For golang/go#70695.
For golang/go#69772.

[git-generate]
find . -type f -name gotypesalias.go -exec rm {} +

Change-Id: Ia9f62875bc73a43f30eda7de873db5d342d8b991
Reviewed-on: https://go-review.googlesource.com/c/exp/+/650135
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Cherry Mui <[email protected]>

Author: dmitshur