Remove Event.wrapper for MediaNotification telemetry

[Alexandru2909]

Breakout from #21292.

┆Issue is synchronized with this Jira Task

[LaurentiuApahideanSV]

I tested the issue on Firefox Nightly 2022-4-12 by interacting with videos and observing the events.
When a video or audio starts and is paused
{
"timestamp": 15714,
"category": "media_state",
"name": "play"
},

{
"timestamp": 22335,
"category": "media_state",
"name": "pause"
},

When a video is put in fullscreen mode
{
"timestamp": 26244,
"category": "media_state",
"name": "fullscreen"
},
When a video is put in picture in picture mode
{
"timestamp": 28956,
"category": "media_state",
"name": "picture_in_picture"
},
When audio is started and paused from the push notification
{
"timestamp": 14138,
"category": "media_notification",
"name": "pause"
},

{
"timestamp": 15384,
"category": "media_notification",
"name": "play"
},

When audio is started and paused from the tabs tray
{
"timestamp": 7515,
"category": "tab",
"name": "media_play"
},

{
"timestamp": 8910,
"category": "tab",
"name": "media_pause"
},
Glean Dashboard

Device used:

• OnePlus 6T (Android 9)