Merge branch 'patch-avs-dom-errors-metrics' into 'master'

Add DOM Errors metric.

See merge request !6361

(cherry picked from commit 643d59b7)

d1bc4fae Add DOM Errors metric.
7ab75615 Fix PON Metrics.
7 jobs for !6363 with cherry-pick-643d59b7 in 26 minutes and 6 seconds (queued for 7 seconds)
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