Fix a couple of regular expressions.

Our old NetBSD regex implementation didn't care, but the current NetBSD
implementation rejects unquoted `{` and `}`s that aren't actually part
of a repetition. glibc shares this behavior.

Interestingly, the new NetBSD code was itself an sync with FreeBSD, so
although macOS right now allows this (as Android did), they may well
switch too.

Anyway, this way of writing the regular expressions is strictly correct,
so regardless of whether or not we can actually land this change to the
regex implementation without causing app compat chaos, we should fix
this test.

Bug: http://b/258469149
Test: treehugger
Change-Id: I85bf5d8f557a4fe5ac5ebeea565892d36da30b55