Improve interactive tooltip hover behaviour

This gives the interactive tooltip a more natural hover behaviour by removing
the full screen div behind it. This allows the target button to keep its hover
state, for example.

This also removes the click to close behaviour, which was too easy to trigger
accidentally.

Fixes https://github.com/vector-im/riot-web/issues/10179
Fixes https://github.com/vector-im/riot-web/issues/10222
Fixes https://github.com/vector-im/riot-web/issues/10225

res/css/views/elements/_InteractiveTooltip.scss

@@ -19,16 +19,6 @@ limitations under the License.
     z-index: 5000;
 }
 
-.mx_InteractiveTooltip_background {
-    position: fixed;
-    top: 0;
-    left: 0;
-    width: 100%;
-    height: 100%;
-    opacity: 1.0;
-    z-index: 5000;
-}
-
 .mx_InteractiveTooltip {
     border-radius: 3px;
     background-color: $interactive-tooltip-bg-color;