[mono-service] log service name when reporting ExitCode != 0

This nitpick was forgotten in this commit:
https://github.com/mono/mono/commit/4b3e9b3874334a55a9de3534f298ddbe891d94bd
[HttpWebRequest] Assertion message nitpicks in new timeout tests

The timeout tests I added recently* had a missing assertion message and
one with a couple of typos.

* https://github.com/mono/mono/commit/96be7828510a1fb14dab07eed1e93dc1a3a7dd84
Merge pull request #645 from knocte/nitpicks

Fix couple of nitpicks in mono-service and HttpWebRequest-Tests