Build/Test Tools: Run the PHP container with PID > 1 so Ctrl+C works correctly.

This allows for cancellation of operations in the PHP container, such as a PHPUnit test suite run.

Fixes #55702


git-svn-id: https://develop.svn.wordpress.org/trunk@53628 602fd350-edb4-49c9-b593-d223f7449a82

docker-compose.yml

@@ -52,6 +52,9 @@ services:
     depends_on:
       - mysql
 
+    # The init directive ensures the command runs with a PID > 1, so Ctrl+C works correctly.
+    init: true
+
   ##
   # The MySQL container.
   ##