test: stabilize test-run-tests.t output
We have reached a point where the duration in JSON reports of
`test-run-tests.t` were greater or equal than 10 seconds, which doesn't match
anymore the regex. For example here:
https://ci.octobus.net/blue/organizations/jenkins/MercurialPy2/detail/MercurialPy2/276/pipeline
```
"diff": "", ? (re)
- "end": "\s*[\d\.]{4,5}", ? (re)
+ "end": "10.040",
"result": "skip", ? (re)
```
Instead of accepting more characters, I changed the regex to accept any number
of digits before the `.` then 3 or 4 digits after. This way the regex is more
precise (only one `.` is authorized and we can ensure that the precision
doesn't change).
Differential Revision: https://phab.mercurial-scm.org/D5966
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.