Using the sed script from
https://gitlab.com/gitlab-org/gitlab-ce/issues/59758

Updates changed method names and fixes spec failures

Fix failing spec in spec/controllers/admin/hooks_controller_spec.rb

attr_encrypted expects models to have their attribute methods defined,
or it will override them with standard Ruby accessors. Migration specs
that rolled back the state of the database after columns were migrated
to encrypted values were interfering with these definitions. To ensure
that the SystemHook specs pass, we need to call
`SystemHook.define_attribute_methods` to ensure that attr_encrypted sees
the right methods that reflect the latest state of the database.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/8234

Use data_source_exists? where possible instead of table_exists? in order to be Rails5 compatible

Signed-off-by: Rémy Coutable <remy@rymai.me>

This is useful for migration tests that relies on factories and that are
very old and/or tedious to modify to not use factories.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

We might also want to consider reduce the number of
connections in the tests. However I just tried setting it to 1
and that doesn't seem enough for feature tests.

So that we could make sure migration tests could run even if
geo is not setup in EE.

This is because we have a model like this:

``` ruby
class Geo::BaseRegistry < ActiveRecord::Base
  def self.connection
    raise 'Geo secondary database is not configured' unless Gitlab::Geo.geo_database_configured?

    super
  end
end
```

This makes it possible to test migration on the schema this migration
was written for, without a need to specify a previous schema version
manually.