Purpose of this commit is to clean a bit the test mode of surveys before
working a bit on ACLs and survey access. Currently when taking a survey
with a magic 'phantom' token it generates a test answer allowing to go
through the survey process. However it has several drawbacks :

 * 'phantom' is not a real token. Token parameter should be used only for
   real tokens and avoid having corner case when managing simple parameter;
 * token should only be used to ensure people have been granted access to
   answering surveys;
 * it is currently available for every users;
 * it is pure unwanted magic;

In this commit we add a separate route for testing surveys that create the
test answer and then redirects to the survey with this answer. It is now
also limited to survey managers or survey officers testing their own surveys.

Survey JS tour now uses the standard URL and not the testing one. Indeed as
testing is now limited to survey officers and managers tour should test
real life use cases.

This commit is linked to task ID 1916034 and PR #29339.