Remove calls to enable_lock_retries! from migrations

Leonardo da Rosarequested to merge
542168-remove-enable-lock-retries-from-migrations-2 into master

What does this MR do and why?

Remove calls to enable_lock_retries! from migrations. The lock-retry mechanism is enabled by default for all transactional migrations.

This is the first step before removing https://gitlab.com/gitlab-org/gitlab/blob/da2305aacbe800873fc88382cee45c1e112170d2/lib/gitlab/database/migration.rb#L10-10

Related to #542168 (closed)

Edited by Leonardo da Rosa

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