Fix ERB syntax error

In the dea.yml.erb template file, <% p("dea_next.streaming_timeout") %> doesn't print the value, it should be changed to <%= p("dea_next.streaming_timeout") %>.


Ruby ERB Syntax:
```
<% %>
Executes the ruby code within the brackets. It’s for any Ruby code, but doesn’t output the results (e.g. if statements).

<%= %>
Prints something into erb file. It’s for outputting the results of Ruby code.
```