[FIX] survey: let Chart.js handle the session graph max height automatically

Before this commit, the graph y scale in the survey manager screen was based on
the attendees count. But is some attendees do not answer the question, the bars
never reach the maximum height of the graph, and bars can stay really small.

Example: 10 attendees - 4 answers - A: 1 / B: 1 / C: 2

10 |
   |
   |
   |       |
0  |_|__|__|_
     A  B  C

After this commit, the max height of the graph is not set on the graph. So the
chart lib will handle itself the height and will adapt automatically the bars
height in function of the data given to the graph. Bars will always take full
height space, relatively to the count of the most voted answer.

Example: 10 attendees - 4 answers - A: 1 / B: 1 / C: 2

2  |       |
   |       |
   | |  |  |
0  |_|__|__|_
     A  B  C

Task ID: 2351455

closes odoo/odoo#59106

Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>

0 files changed, 0 insertions, 0 deletions