Update test-format to reopen an existing database with different config

Currently, test-format is not compatible to re-open(-R option) an existing database with a different config (-c option). In WT-7599 we encountered a problem in upgrade/downgrade testing that some we are trying to figure out a solution in which an existing database will be re-opened by test-format with a different configuration option.

These changes will be backported to the 5.0, 4.4, and 4.2 branches.