Remove testcase generating code from util_SettingsMerge so it can be reused in
new tests.
The hash value expected in util_SettingsMerge changes as a result of this, but
only because the testcases are generated in a different order, not because any
cases are added or removed. It is possible to verify this with:
SETTINGS_MERGE_TEST_OUT=new.txt test/test_bitcoin --run_test=util_tests/util_SettingsMerge
git checkout HEAD~1
make test/test_bitcoin
SETTINGS_MERGE_TEST_OUT=old.txt test/test_bitcoin --run_test=util_tests/util_SettingsMerge
diff -u <(sort old.txt) <(sort new.txt)
The new output is a little more readable, with simpler testcases sorted first.
