Remove "Add to friends" text on new page header button

[Kristina Hoeppner]

Follow-on to bug #1815829:

Problem only on Mahara master (soon to be 19.04):

There is still the button label "Add to friends" on the profile page of a user when they allow friends to be auto-added. This shouldn't be the case. We should only see the icon and the text should be there as tool tip.

To replicate:

1. Set up two users.
2. User 1 should have the account setting "Friends control" set to "New friends are automatically authorised".
3. Log in as user 2 and go to the profile page of user 1.
4. Actual result: You see the button "Add to friends" with icon and text (see attached screenshot).
   Expected result: You see the button only with the icon and the text is in a tool tip that you see when you hover over it.

[Mahara Bot (dev-mahara)]

Patch for "master" branch: https://reviews.mahara.org/9676

[Mahara Bot (dev-mahara)]

Reviewed: https://reviews.mahara.org/9676
Committed: https://git.mahara.org/mahara/mahara/commit/f127f134cfd499daab6f9a6cf044487b703fdccb
Submitter: Robert Lyon (<email address hidden>)
Branch: master

commit f127f134cfd499daab6f9a6cf044487b703fdccb
Author: Lisa Seeto <email address hidden>
Date: Thu Mar 28 16:00:04 2019 +1300

Bug 1821859: Remove "Add to friends" text on new page header button

updated the pieform to conditionally display the button label
added title to the forms button element

behatnotneeded

Change-Id: I8ccbb92b64680b0d33a33ea27671bd2a21855a77
Signed-off-by: Lisa Seeto <email address hidden>