fix: panic when log level is not defined (#3639) #5657

Job	Run time
API Server unit tests	2m 32s
CLI unit tests	20s
Build docker image	5m 50s
config-e2e	1s
WebUI unit tests	2m 7s
Agent unit tests	31s
CLI smoke tests (local)	49s
CLI smoke tests (docker)	53s
Tracetesting API Server (NATS)	17s
Test examples (collector)	43s
Tracetesting API Server (InMemory)	4m 19s
Test examples (tracetest-jaeger)	40s
Test examples (tracetest-opensearch)	7m 45s
Test examples (tracetest-tempo)	37s
WebUI End-to-end tests (1)	3m 34s
Test examples (tracetest-provisioning-env)	50s
WebUI End-to-end tests (2)	4m 10s
Test examples (tracetest-signoz)	2m 22s
CLI e2e tests (8, 0)	1m 31s
WebUI End-to-end tests (3)	3m 34s
CLI e2e tests (8, 1)	1m 18s
WebUI End-to-end tests (4)	1m 0s
CLI e2e tests (8, 2)	55s
WebUI End-to-end tests (5)	52s
CLI e2e tests (8, 3)	1m 19s
WebUI End-to-end tests (6)	3m 37s
CLI e2e tests (8, 4)	1m 17s
CLI e2e tests (8, 5)	1m 7s
WebUI End-to-end tests (7)	3m 28s
WebUI End-to-end tests (8)	3m 35s
CLI e2e tests (8, 6)	3m 6s
CLI e2e tests (8, 7)	3m 43s
	1h 8m 42s

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