Post push fix

Problem:
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The ndb_metadata_upgrade_80_minor test involves restoring a backup
consisting of foreign keys. This backup is created on a little-
endian system and restoring it on big-endian systems leads to an
error while restoring the foreign keys

Fix:
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Move the foreign key related cases into a separate test and disable
it on big-endian systems

Change-Id: I9f6b3ad1d57fc46280f3336af53688970159eacc