managetests: fix paths to scripts

Signed-off-by: Mattia Rizzolo <mattia@debian.org>

managetests.json

 {
     "build": [
         ["./run", "build_scss"],
-        ["{{base}}/run", "init", "{{base}}/data"]
+        ["./run", "init", "{{base}}/data"]
     ],
     "run": [
-        "{{base}}/run", "run",
+        "{{base}}/build/run", "run",
         "-g", "{{gunicorn_config_file}}",
         "{{base}}/data"
     ]