Merge branch 'jc/push-2.0-default-to-simple' (early part)

Adjust our tests for upcoming migration of the default value for the "push.default" configuration variable to "simple" from "mixed". * 'jc/push-2.0-default-to-simple' (early part): t5570: do not assume the "matching" push is the default t5551: do not assume the "matching" push is the default t5550: do not assume the "matching" push is the default t9401: do not assume the "matching" push is the default t9400: do not assume the "matching" push is the default t7406: do not assume the "matching" push is the default t5531: do not assume the "matching" push is the default t5519: do not assume the "matching" push is the default t5517: do not assume the "matching" push is the default t5516: do not assume the "matching" push is the default t5505: do not assume the "matching" push is the default t5404: do not assume the "matching" push is the default