Fix: Duplicated Dockerfile and .dockerignore when generating the project with Rails 7.1

[sanG-github]

Issue

We're facing two duplicating errors when generating the project from our template that should be fixed ASAP👷‍

Expected

The template can generate a project successfully and there are no duplications or errors caused to the user

Steps to reproduce

Both ways to generate the project faced the same issue.

1. Run `rails new app_name -m https://raw.githubusercontent.com/nimblehq/rails-templates/main/template.rb` as documented.

Or

1. Clone our rails template locally
2. Run `rails new app_name -m ./template.rb`

[malparty]

Note that this only occurs since Rails 7.1, as Rails introduced a default Dockerfile in the base template 😇

[malparty]

Can be fixed with simple

remove_file 'Dockerfile'
remove_file '.dockerignore'

Later we might want to reuse these default dockerfiles but that's in research for the current sprint 👍