doc/progs: remove flaky timing-sensitive test

Package time already has enough inherently flaky tests covering its
behavior.  No need for more of them.

Fixes #10632.

Change-Id: I1229e9fcc2e28ba2c9b0b79f73638e35dbbe8bbf
Reviewed-on: https://go-review.googlesource.com/9517Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

doc/progs/run.go

@@ -169,7 +169,7 @@ var tests = []testcase{
 	{"image_package6", `^8 4 true$`},
 
 	// other
-	{"go1", `^Christmas is a holiday: true Sleeping for 0.123s.*go1.go already exists$`},
+	{"go1", `^Christmas is a holiday: true .*go1.go already exists$`},
 	{"slices", ""},
 }