[FIX] website_event_track_live: fit divs to video player size

Issue introduced in https://github.com/odoo/odoo/pull/95450

After migrating to 5.1.3 Bootstrap, the col-12 element no
longer had implicit position-relative attribute, meaning that
o_wesession_track_main div was no longer position-relative.

Therefore, children position-absolute elements for loading
and track suggestion at the start / end of the video became
absolute to the window instead, and format failed to match
the video frame anymore, as it should have.

-> FIX : add manually the position-relative back on the live
track container element (see o_wevent_event_track_live).
We also add JS check to make sure we add position-relative
even if templates are not updated in stable, as the screen
is very disturbed otherwise.

Task-3215833

closes odoo/odoo#115430

X-original-commit: 643cdc649bf14d51528e9502266bfbcd62576b6e
Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>

addons/website_event_track_live/static/src/js/website_event_track_live.js

@@ -15,6 +15,10 @@ publicWidget.registry.websiteEventTrackLive = publicWidget.Widget.extend({
     start: function () {
         var self = this;
         return this._super(...arguments).then(function () {
+            // Remove me in master. Make sure position-relative is set on o_wevent_event_track_live
+            // in stable otherwise suggestion screen is relative to the window, not to the youtube
+            // frame, breaking screen display. Loading wheel would not be centered either.
+            self.$el.addClass('position-relative');
             self._setupYoutubePlayer();
         });
     },

addons/website_event_track_live/views/event_track_templates_page.xml

@@ -18,7 +18,7 @@
     <!-- Add video -->
     <xpath expr="//div[@name='o_wesession_track_main']//div" position="before">
         <t t-set="show_youtube_frame" t-value="track.youtube_video_url and (track.is_youtube_replay or track.is_track_soon or track.is_track_live or track.is_track_done)" />
-        <div t-if="show_youtube_frame" class="flex-grow-1 o_wevent_event_track_live"
+        <div t-if="show_youtube_frame" class="flex-grow-1 o_wevent_event_track_live position-relative"
             t-att-data-track-id="track.id"
             t-att-data-track-name="track.name"
             t-att-data-track-website-image-url="track.website_image_url"