[release-branch.go1.25] test/fixedbugs: remove issue46234 test timeout

issue46234 is flaky on slow machines due to the possibility of running
into the constant timeout. Delete it in favor of timeouts applied at a
higher level.

Note that that test timeout already got increased from 30s to 45s in
CL 382774, but it was still not enough.

For #50973.
Fixes #78318.

Cq-Include-Trybots: luci.golang.try:go1.25-darwin-amd64_15,go1.25-darwin-amd64_14
Change-Id: I809249a05c6ca65fb6c44375c8de5758f21dbb91
Reviewed-on: https://go-review.googlesource.com/c/go/+/747520
Auto-Submit: Quim Muntal <quimmuntal@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
(cherry picked from commit b0057a4e0cacb4c920c9eb82216b63ed60d6e9fb)
Reviewed-on: https://go-review.googlesource.com/c/go/+/758641
Auto-Submit: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: David Chase <drchase@google.com>