Revert "testing: delete unused stopAlarm()"
Revert "testing: delete unused stopAlarm()"

This reverts commit ed8c62b7fb47b717dc2adc9f6d0c90c924c67712.

Turns out it was needed in later commits.

Change-Id: I07a7bc2429976d8a5a89f915a11625c118b85500
Reviewed-on: https://go-review.googlesource.com/36113
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Joe Tsai <7277d7402195d5c2006c89f45718cf82bb3e527f@gmail.com>

polyverse-security/go,polyverse-security/go,ImJasonH/go,linux-on-ibm-z/go,akutz/go,CAFxX/go,akutz/go,cloudflare/go,codestation/go,CAFxX/go,ImJasonH/go,codestation/go,Cofyc/go,linux-on-ibm-z/go,cloudflare/go,derekmarcotte/go,linux-on-ibm-z/go,golang/go,vsekhar/elastic-go,codestation/go,nawawi/go,ImJasonH/go,derekmarcotte/go,josharian/go,golang/go,akutz/go,derekmarcotte/go,codestation/go,linux-on-ibm-z/go,golang/go,linux-on-ibm-z/go,akutz/go,akutz/go,josharian/go,josharian/go,josharian/go,josharian/go,polyverse-security/go,CAFxX/go,nawawi/go,nawawi/go,codestation/go,vsekhar/elastic-go,nawawi/go,nawawi/go,CAFxX/go,CAFxX/go,vsekhar/elastic-go,christopher-henderson/Go,polyverse-security/go,josharian/go,vsekhar/elastic-go,vsekhar/elastic-go,linux-on-ibm-z/go,golang/go,akutz/go,akutz/go,ImJasonH/go,polyverse-security/go,derekmarcotte/go,linux-on-ibm-z/go,golang/go,Cofyc/go,ImJasonH/go,linux-on-ibm-z/go,golang/go,josharian/go,Cofyc/go,Cofyc/go,Cofyc/go,ImJasonH/go,derekmarcotte/go,Cofyc/go,CAFxX/go,golang/go,cloudflare/go,derekmarcotte/go,cloudflare/go,derekmarcotte/go,cloudflare/go,CAFxX/go,vsekhar/elastic-go,ImJasonH/go,polyverse-security/go,CAFxX/go,vsekhar/elastic-go,nawawi/go,cloudflare/go,polyverse-security/go,codestation/go,polyverse-security/go,codestation/go,Cofyc/go,vsekhar/elastic-go,cloudflare/go,nawawi/go,codestation/go,Cofyc/go,nawawi/go,cloudflare/go,josharian/go,ImJasonH/go,akutz/go,golang/go,derekmarcotte/go