[IMP] point_of_sale,stock_*: Remove StockAccountTestCommon setup class

addons/mrp_landed_costs/tests/test_stock_landed_costs_mrp.py

addons/point_of_sale/tests/common.py

addons/purchase_stock/tests/test_average_price.py

addons/purchase_stock/tests/test_fifo_price.py

addons/purchase_stock/tests/test_fifo_returns.py

addons/stock_account/tests/common.py

...tests/test_anglo_saxon_valuation_reconciliation_common.py

addons/stock_dropshipping/tests/test_lifo_price.py

addons/stock_dropshipping/tests/test_stockvaluation.py

addons/stock_landed_costs/tests/test_stock_landed_costs.py

...ck_landed_costs/tests/test_stock_landed_costs_rounding.py

addons/stock_landed_costs/tests/test_stockvaluationlayer.py