fix: make server-core-integration observers be typed #7670

Job	Run time
Typecheck and Lint Core	6m 36s
Build gateways (playout-gateway)	3m 5s
Build Core and publish docker image	11m 3s
Build gateways (mos-gateway)	3m 22s
Check for multiple library versions	2m 52s
Build gateways (live-status-gateway)	3m 12s
Publish Docs	5m 4s
Lint Package (blueprints-integration)	2m 19s
Lint Package (server-core-integration)	2m 27s
Test Core	6m 7s
Lint Package (playout-gateway)	2m 24s
Test Package (blueprints-integration, 14.x)	52s
Lint Package (mos-gateway)	3m 2s
Test Package (blueprints-integration, 16.x)	2m 34s
Lint Package (corelib)	3m 7s
Test Package (blueprints-integration, 18.x)	2m 25s
Lint Package (shared-lib)	2m 7s
Test Package (server-core-integration, 14.x)	56s
Lint Package (job-worker)	3m 59s
Test Package (server-core-integration, 16.x)	2m 14s
Lint Package (openapi)	2m 48s
Test Package (server-core-integration, 18.x)	2m 54s
Lint Package (live-status-gateway)	3m 21s
Test Package (shared-lib, 14.x)	41s
Test Package (shared-lib, 16.x)	2m 33s
Test Package (shared-lib, 18.x)	1m 54s
Test Package (14.x, corelib, true)	1m 13s
Test Package (14.x, job-worker, true)	3m 22s
Test Package (16.x, openapi)	2m 34s
Test Package (18.x, openapi)	2m 28s
Release Lib	0s
	1h 33m 35s

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