Stop ignoring old .env.erb files from Kamal 1 (rails#53000)

`.env.erb` files are not generated any more in new Rails apps, so this commit removes them from the ignore files. Kamal 2 now manages secrets with .kamal/secrets, and this file is meant to be safe for git by
default.

Author: jeromedalbert

railties/lib/rails/generators/rails/app/templates/dockerignore.tt

@@ -7,9 +7,8 @@
 # Ignore bundler config.
 /.bundle
 
-# Ignore all environment files (except templates).
+# Ignore all environment files.
 /.env*
-!/.env*.erb
 
 # Ignore all default key files.
 /config/master.key

railties/lib/rails/generators/rails/app/templates/gitignore.tt

@@ -7,9 +7,8 @@
 # Ignore bundler config.
 /.bundle
 
-# Ignore all environment files (except templates).
+# Ignore all environment files.
 /.env*
-!/.env*.erb
 
 # Ignore all logfiles and tempfiles.
 /log/*