test: changed test1 of test-vm-timeout.js

test: changed test1 of test-vm-timeout.js so that entire error message
would be matched in assert.throw.

Before test 1 of test-vm-timeout.js would match any error,
now it looks specifically for the error message
"Script execution timed out."

PR-URL: https://github.com/nodejs/node/pull/11590


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>