Revert "Remove tax adjustment when its associated tax rate is gone while recalculating tax.."

This reverts commit 776bb6e012cb22b54204473447d1918f5b43a20d.
Revert "Adjustment may be associated with a promotion that is deleted already."

This reverts commit 0177096127273e1c9c57be81675bffec6afbe1c1.
Revert "Keep adjustments when assocaited tax rate or promotion is deleted. By doing this an order that has those adjustments applied will still have it (better user experience). To avoid referencing non-exist prmotion action this fix also makes Spree::Promotion::Actions paranoid"

This reverts commit f2f5557d4a8726307b273456dc80679a9cc4188f.
Revert "Fix Spree issue https://github.com/spree/spree/issues/4771"

This reverts commit e57457cf84c720fd9d351374a566b00a20725ee6.
Only destroy tax adjustment for open order when the associated tax rate is deleted. For closed order just nullify the source_id.
Merge branch '1838' into 2-2-nemo-stable