When a table with foreign keys are created, first the index is created
and then during foreign key creation, those indexes are loaded into the
ndbapi's dict cache. But when the `create table` ultimately fails due
to some FK issue, those indexes in the cache are not invalidated. Due
to this, any upcoming `create table` with some similarly named indexes
as the previous failed DDL gets all mixed up and gives out inconsistent
results. This patch invalidates the indexes in cache on failure.