[FIX] chart: wrong label format for date chart

Date charts would always have a datetime format for the labels, no
matter the format of the data. They would also be truncated, which
we probably don't want for dates.

The issue is that the date charts had a callback for the ticks
using `truncateLabel`, and `getLabelForValue` which seems bugged in
date charts[1].

This commit removes the tick callback for date charts, letting the
luxon time adapter format the dates.

[1] chartjs/Chart.js#12128

closes #7267

Task: 4908471
X-original-commit: 935b5ec
Signed-off-by: Rémi Rahir (rar) <rar@odoo.com>

Author: hokolomopo

src/helpers/figures/charts/runtime/chartjs_scales.ts

@@ -105,6 +105,7 @@ export function getLineChartScales(
     };
     Object.assign(scales!.x!, axis);
     scales!.x!.ticks!.maxTicksLimit = 15;
+    delete scales?.x?.ticks?.callback;
   } else if (axisType === "linear") {
     scales!.x!.type = "linear";
     scales!.x!.ticks!.callback = (value) => formatValue(value, { format: labelFormat, locale });

tests/figures/chart/__snapshots__/chart_plugin.test.ts.snap

@@ -264,7 +264,6 @@ exports[`Linear/Time charts snapshot test of chartJS configuration for date char
           },
           "stacked": undefined,
           "ticks": {
-            "callback": [Function],
             "color": "#000000",
             "maxTicksLimit": 15,
             "padding": 5,

tests/figures/chart/chart_plugin.test.ts

@@ -2662,6 +2662,7 @@ describe("Linear/Time charts", () => {
     );
     let config = getChartConfiguration(model, chartId);
     expect(config.options?.scales?.x?.type).toEqual("time");
+    expect(config.options?.scales?.x?.ticks?.callback).toBeUndefined();
   });
 
   test("time axis for line/bar chart with formulas w/ date format as labels", () => {