[FIX] web: trackback when formatFloat value is undefined

steps to produce:
- when measure field value set null if value is zero.
- try to open cohort/graph view measure.
- trackback occurs 'value.toFixed is not a function'.

Fix:
This commit, fixes the trackback when the measure value is null or undefined.
It occurs when the measure field value is null in a particular condition.

closes odoo/odoo#135207

Task: 3502869
Related: odoo/enterprise#47572
Signed-off-by: Xavier Bol (xbo) <xbo@odoo.com>

addons/web/static/src/views/graph/graph_renderer.js

@@ -2,7 +2,7 @@
 
 import { _t } from "@web/core/l10n/translation";
 import { getBorderWhite, DEFAULT_BG, getColor, hexToRGBA } from "@web/core/colors/colors";
-import { formatFloat } from "@web/core/utils/numbers";
+import { formatFloat } from "@web/views/fields/formatters";
 import { SEP } from "./graph_model";
 import { sortBy } from "@web/core/utils/arrays";
 import { loadJS } from "@web/core/assets";