Fix save parser test, and fix error in parsing old saves

[chennin]

1. Old saves that don't have council_positions were failing to parse. Add an existence check for the data structure in _update_council_positions().

2. The test for a full save parse did not propagate an exception back to the tester, causing false negatives (it only successfully tested the existence of the rust save parser). By setting config.CONFIG.debug_mode to True we hit code that propagates the exception, and the test properly fails when a save fails to parse.

Repro: python -m pytest test/parser_test.py -k "test_real_save" -s

1. On v6, prints a stack trace but does NOT fail the test
2. On this branch, does not print a stack strace and does not fail the test.
3. On this branch, if you remove the check-and-early-return for missing council_positions, the parse prints a trace and the test fails.

The stack trace:

2023-11-30 20:34:08,493 - stellarisdashboard.parsing.timeline - INFO - nexitronawareness_1329922464 2565.06.02   - Processing council
2023-11-30 20:34:08,517 - stellarisdashboard.parsing.timeline - ERROR - nexitronawareness_1329922464 2565.06.02 Rolling back changes to database...
Traceback (most recent call last):
  File "/home/alucard/stellaris-dashboard/stellarisdashboard/parsing/timeline.py", line 60, in process_gamestate
    self._process_gamestate(db_game)
  File "/home/alucard/stellaris-dashboard/stellarisdashboard/parsing/timeline.py", line 110, in _process_gamestate
    data_processor.extract_data_from_gamestate(
  File "/home/alucard/stellaris-dashboard/stellarisdashboard/parsing/timeline.py", line 2047, in extract_data_from_gamestate
    self._update_council_positions(countries_by_id, leaders_by_id)
  File "/home/alucard/stellaris-dashboard/stellarisdashboard/parsing/timeline.py", line 2052, in _update_council_positions
    self._gamestate_dict["council_positions"]["council_positions"].items()
KeyError: 'council_positions'

This was hidden from all automated tests before!

NB I haven't actually checked the effect in the GUI of skipping _update_council_positions() - I haven't played Stellaris since before the council existed :). I'd appreciate a large, end-game 3.10.x (preferably 3.10.2!) save to add to the test cases.

[eliasdoehne]

👍