flash-container duplicate in workflows.html.erb (small fix)

[kennethrioja]

Summary of changes

• Deleting div flash-container in workflows.html.erb

Motivation and context

Stumbled upon this duplication while logging in from the Workflows page

Screenshots

Checklist

• I have read and followed the CONTRIBUTING guide.
• I confirm that I have the authority necessary to make this contribution on behalf of its copyright owner and agree
  to license it to the TeSS codebase under the
  BSD license.

[fbacall]

We have the following code:
https://github.com/ElixirTeSS/TeSS/blob/master/app/controllers/workflows_controller.rb#L27

https://github.com/ElixirTeSS/TeSS/blob/master/app/views/layouts/_header.html.erb#L96-L100

that was supposed to prevent this duplication occurring, but it looks like it was not applied to all cases where the workflows layout is used.

I think you should just remove the @skip_flash_messages_in_header variable and its uses

[kennethrioja]

I just removed @skip_flash_messages_in_header and its uses but kept the flash-container deleted as it is almost a duplicate from the one in _header.html.erb

-> I checked where class="workflows-container" was used, and I don't find any specific use to this specific flash-container