Limit test execution time (#5484)

This should protect us from unnoticed hangs, which happen sometimes and
waste CI and developer time.
Currently, the limit is 15s per test, which should be enough in normal
conditions.

tests/python/pytest.ini

@@ -1,2 +1,6 @@
 [pytest]
+required_plugins = pytest-timeout
 addopts = --verbose --capture=tee-sys
+# We expect no regular individual test to run too long
+# can be overridden for specific tests with a test decorator
+timeout = 15

tests/python/requirements.txt

@@ -1,4 +1,5 @@
 pytest==6.2.5
+pytest-timeout==2.1.0
 requests==2.26.0
 deepdiff==5.6.0
 boto3==1.17.61