Random behat failures on several places with a "Search" name/button

In MDL-65087 the aria-label="Search" has been added to the message drawer. Since then, some random failures seem to affect anything with a "Search" name/button around because of conflicts with the hidden aria-label attribute in messaging.

Possible ways to proceed to fix it:

1. Change the aria-label to something like "Search contacts and messages" to stop matching so many elements.
2. Stop behat looking by aria-label.