buildperf: Tweak tooltip positioning for usability

The tooltop contains a key hyperlink to make the graphs usable. Make
it easier to click on the link by removing the space between the data
point and the tooltip.

(From OE-Core rev: a090076e42eb9b41da55fc01ccbbb68f9b8a8cb8)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/build_perf/html/measurement_chart.html

@@ -40,7 +40,7 @@
       trigger: 'axis',
       enterable: true,
       position: function (point, params, dom, rect, size) {
-        return [point[0]+20, '10%'];
+        return [point[0], '0%'];
       },
       formatter: function (param) {
         const value = param[0].value[1]
@@ -93,7 +93,7 @@
       trigger: 'axis',
       enterable: true,
       position: function (point, params, dom, rect, size) {
-        return [point[0]+20, '10%'];
+        return [point[0], '0%'];
       },
       formatter: function (param) {
         const value = param[0].value