The level in GstAudioLevelMeta is represented as a signed 8bit value from 0 to
127 (with 127 meaning silence). When converting from double, make sure to clip
the value, this also prevent integer overflow in the conversion. This fixes an
issue where a lower then -127db is reported and random level with near silent
streams (due to integer overflow).
Fixes#4068
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/8012>