Increase delay affordance in waitforlock test

[jcharaoui]

Short description

This increases the maximum delay in the waitforlock unit test so we avoid failing frequently on slower/busier hosts.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document and added a Signed-off-by annotation to each of my commits
• read and accepted the AI Policy document and added Generated-by or Assisted-by annotations to each of my commits created with the help of an AI agent
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)

[jcharaoui]

Example of this test failing because of the too short delay in Debian's CI: https://ci.debian.net/packages/o/openvox/testing/armhf/74660446/

I have reproduced the problem locally using restricted CPU quotas and can confirm this change fixes the problem.