[bitnami/discourse] Allow for DISCOURSE_SMTP_DOMAIN to be set via docker

[shageman]

Description of the change

This change exposes the config option smtp_domain as env variable DISCOURSE_SMTP_DOMAIN

Benefits

If the hostname doesn't match the email domain, SMTP providers might balk at sending messages. Set this setting to correct that.

Applicable issues

#35676

Additional information

https://meta.discourse.org/t/troubleshoot-email-on-a-new-discourse-install/16326

[carrodher]

Thank you for initiating this pull request. We appreciate your effort. This is just a friendly reminder that signing your commits is important. Your signature certifies that you either authored the patch or have the necessary rights to contribute to the changes. You can find detailed information on how to do this in the “Sign your work” section of our contributing guidelines.

Feel free to reach out if you have any questions or need assistance with the signing process.

[shageman]

@carrodher does the new commit (with signing) look right?

[github-actions]

This Pull Request has been automatically marked as "stale" because it has not had recent activity (for 15 days). It will be closed if no further activity occurs. Thank you for your contribution.

[github-actions]

Due to the lack of activity in the last 5 days since it was marked as "stale", we proceed to close this Pull Request. Do not hesitate to reopen it later if necessary.

[github-actions]

This Pull Request has been automatically marked as "stale" because it has not had recent activity (for 15 days). It will be closed if no further activity occurs. Thank you for your contribution.

[github-actions]

Due to the lack of activity in the last 5 days since it was marked as "stale", we proceed to close this Pull Request. Do not hesitate to reopen it later if necessary.