VOTE-3153: Update login button text.

[daniel-crowder]

Jira ticket

VOTE-3153

Description

Renames user login button to reflect the use of GSA Auth.

Deployment and testing

Post-deploy steps

1. Locally change line 189 in sites/settings.local.php to include $config['config_split.config_split.production']['status'] = TRUE;
2. Locally run drush cim

QA/Testing instructions

1. Goto /user/login and confirm that the login button reads, "Proceed to GSA Auth login"

Checklist for the Developer

• A link to the JIRA ticket has been included above.
• No merge conflicts exist with the target branch.
• Automated tests have passed on this PR.
• A reviewer has been designated.
• Deployment and testing steps have been documented above, if applicable.

Checklist for the Peer Reviewers

• The file changes are relevant to the task objective.
• Code is readable and includes appropriate commenting.
• Code standards and best practices are followed.
• QA/Test steps were successfully completed, if applicable.
• Applicable logs are free of errors.