Merge branch 'yd/use-test-config-unconfig'
Bulk-update of the test suite.
* yd/use-test-config-unconfig:
t5520: use test_config to set/unset git config variables (leftover bits)
t7600: use test_config to set/unset git config variables
t7502: remove clear_config
t7502: use test_config to set/unset git config variables
t9500: use test_config to set/unset git config variables
t7508: use test_config to set/unset git config variables
t7500: use test_config to set/unset git config variables
t5541: use test_config to set/unset git config variables
t5520: use test_config to set/unset git config variables
t4202: use test_config/test_unconfig to set/unset git config variables
t4034: use test_config/test_unconfig to set/unset git config variables
t4304: use test_config to set/unset git config variables
t3400: use test_config to set/unset git config variables