chore: use github var for kurrentdb images #791

Job	Run time
Build (8)	44s
Build (11)	47s
Build (17)	49s
Plugins Tests / Single Node (Plugins)	1m 8s
Plugins Tests / Cluster (Plugins)	1m 1s
Tests (CI) / Tests (CI) / Single node (Streams)	1m 15s
Tests (CI) / Tests (CI) / Secure (Streams)	1m 39s
Tests (CI) / Tests (CI) / Single node (PersistentSubscriptions)	1m 42s
Tests (CI) / Tests (CI) / Secure (PersistentSubscriptions)	1m 49s
Tests (CI) / Tests (CI) / Single node (Telemetry)	1m 15s
Tests (CI) / Tests (CI) / Cluster (Streams)	3m 12s
Tests (CI) / Tests (CI) / Cluster (PersistentSubscriptions)	2m 31s
Tests (LTS) / Tests (LTS) / Single node (Streams)	1m 3s
Tests (LTS) / Tests (LTS) / Single node (PersistentSubscriptions)	1m 24s
Tests (LTS) / Tests (LTS) / Single node (Telemetry)	1m 8s
Tests (LTS) / Tests (LTS) / Cluster (Streams)	1m 9s
Tests (LTS) / Tests (LTS) / Cluster (PersistentSubscriptions)	1m 28s
Tests (LTS) / Tests (LTS) / Secure (Streams)	1m 15s
Tests (Previous LTS) / Tests (Previous LTS) / Secure (Streams)	1m 20s
Tests (LTS) / Tests (LTS) / Secure (PersistentSubscriptions)	1m 46s
Tests (Previous LTS) / Tests (Previous LTS) / Cluster (Streams)	1m 7s
Tests (Previous LTS) / Tests (Previous LTS) / Secure (PersistentSubscriptions)	1m 39s
Tests (Previous LTS) / Tests (Previous LTS) / Cluster (PersistentSubscriptions)	1m 38s
Tests (Previous LTS) / Tests (Previous LTS) / Single node (Streams)	1m 11s
Tests (Previous LTS) / Tests (Previous LTS) / Single node (PersistentSubscriptions)	1m 25s
Tests (Previous LTS) / Tests (Previous LTS) / Single node (Telemetry)	1m 0s
	36m 25s

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