Add some fixes for the trial flow

What does this MR do?

• Fix some syntax errors on _skip_trial.html.haml partial.
• Persist form data after validation error on sign up form.
• Persist form data after validation error on company info form.
• Fix a broken spec.
• Add some missing translations.

Additionally I've found the following issues that are not fixed in this MR

Sometimes the Country dropdown is not loading the list of countries:

When loading the Step 2, the UI transformation for the dropdowns is a bit notorious:

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team