AOF loading: split handling of format errors from unexpected EOF.
Test AOF format error detection.
AOF ability to load truncated files.
Correct cleanup when aborting AOF loading.

Because of the new ability to start with a truncated AOF, we need
to correctly release all the memory on EOF error. Otherwise there is a
small leak, that is not really a problem, but causes a false positive in
the tests that detect memory leaks.
Make aof-load-truncated option actually configurable.
AOF tests fixed turning aof-load-truncated to no.

When aof-load-truncated option was introduced, with a default of "yes",
the past behavior of the server to abort with trunncated AOF changed, so
we need to explicitly configure the tests to abort with truncated AOF
by setting the option to no.
Tests for aof-load-truncated = yes.