How to replace text about [node:url] within a Rules Action?
I would transform your existing rule into 2 separated rules like so:


Create a Rules Component that only performs a Rules Action which is to send an eMail, similar to what you already have in your current Rules Action. But replace the node:title and the node:url by corresponding parameters to execute this Rules Component.
Replace the Rules Action of the rule you already have by the execution of your newly created Rules Component, in which you pass as parameter values:


the title of the node
the appropriate string that matches your domain.com/newsroom/press-release/[path-to-content]



With that, you don't need any PHP, so no str_replace() either.