Change varbinary to varchar in schemas used in examples folder #15997

[arthmis]

Description

This changes usage of varbinary to varchar in schemas used in the /examples folder. Schema fields like keyspace_id that use varbinary are excluded from the change.

Related Issue(s)

This PR fixes #15997

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
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• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

[vitess-bot]

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