fix(AU-VIC): correct AFL Grand Final Friday for 2015, 2020 and 2022

[ryanduguid]

The 1st friday before October rule for AFL Grand Final Friday gives the wrong date in three years, and it also adds the holiday before it existed.

Year	Before	Actual
2015	25 September	2 October
2020	25 September	23 October
2022	30 September	23 September

Sources:

• The Minister appointed the Friday before the Grand Final as a Victorian public holiday under section 7(1)(a) of the Public Holidays Act 1993 in Gazette S 229 of 19 August 2015, so the holiday now starts in 2015.
• The first one was on 2 October 2015 (The New Daily, 17 August 2015).
• Business Victoria lists Friday 23 October for 2020 and Friday 23 September for 2022.

The rule still gives the right date for the other years from 2016 to 2024, so I disabled and enabled the three dates instead of changing it.

I regenerated the AU-VIC fixtures with --writetests --countries AU; only 2015, 2020 and 2022 changed. npm run lint, npx mocha (5,652 passing) and TEST_XXL=1 npx mocha (9,420 passing) pass locally.