tests: fix test_stacktrace_big_recursion failure due to argv (#4346)

Sometimes I see the test failing because the event contains `extras`
with `sys.argv` key in addition to `exception`. There's probably some
state leaking between tests, but regardless this patch should make the
test case slightly more robust.

Signed-off-by: Ihar Hrachyshka <[email protected]>

Author: Ihar Hrachyshka

tests/test_basics.py

@@ -1151,10 +1151,8 @@ def recurse():
     (event,) = events
 
     assert event["exception"]["values"][0]["stacktrace"] is None
-    assert event["_meta"] == {
-        "exception": {
-            "values": {"0": {"stacktrace": {"": {"rem": [["!config", "x"]]}}}}
-        }
+    assert event["_meta"]["exception"] == {
+        "values": {"0": {"stacktrace": {"": {"rem": [["!config", "x"]]}}}}
     }
 
     # On my machine, it takes about 100-200ms to capture the exception,