Add a charm config to add custom annotations to loadbalancers created by traefik #1153

Job	Run time
Terraform / Terraform lint	5s
PR / Check against ignorelist	7s
PR / Quality Checks / Check the CHARMHUB_TOKEN secret	1s
PR / Quality Checks / Inclusive naming / check	7s
PR / Quality Checks / Linting / Lint	28s
PR / Quality Checks / Scenario Tests / Scenario tests	1m 15s
PR / Quality Checks / Static Analysis / Static Analysis of Charm	32s
PR / Quality Checks / Static Analysis / Static Analysis of Libs	27s
PR / Quality Checks / Unit Tests / Unit tests	41s
PR / Quality Checks / Check libraries	31s
PR / Quality Checks / CodeQL analysis / Analyze (python)	1m 21s
PR / Quality Checks / Integration Tests / Integration Tests	40m 2s
	45m 37s

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