Bump actions/checkout from 5.0.1 to 6.0.0 #6396

Job	Run time
Unit Tests	3m 2s
Unit tests with race condition detection	3m 39s
Lint	2m 9s
Build Unsigned Snapshot	8m 37s
Cache Dependencies	0s
Upgrade Tests (redhatenterprise, 9)	2m 43s
Upgrade Tests (alpine, 3.22)	2m 7s
Integration Tests (alpine, 3.22)	5m 15s
Integration Tests (ubuntu, 24.04)	6m 5s
Upgrade Tests (ubuntu, 24.04)	2m 46s
Integration Tests (redhatenterprise, 9)	5m 40s
Performance Tests	8m 33s
Load Tests	0s
Metrics Integration Tests - Official Plus Images	0s
Integration Tests - Official OSS Images	0s
Metrics Integration Tests - Official OSS Images	0s
Integration Tests - Official Plus Images	0s
	50m 36s

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