Fix a case with empty secret CI/CD variables

What does this MR do?

This merge request updates attr_encrypted gem to fix the problem with empty secret variables ➡ gitlab-org/gitlab-ce#31929.

A pull request introduced a bug that results in not initializing encrypted attributes correctly, what eventually results in swallowing errors / exceptions and CI/CD secret variables being empty without any errors propagated to the sentry.

This happens when we somehow starve connection pool, and are not able to initialize database connection before loading classes using attr_encrypted attributes.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• End-to-end tests passing

What are the relevant issue numbers?

Closes gitlab-org/gitlab-ce#31929