Update testing error logging in JSON unmarshal tests to use %v instea… #572

Job	Run time
Linters (Static Analysis) for Go (ubuntu-20.04, 1.15.x)	17s
Linters (Static Analysis) for Go (ubuntu-20.04, 1.16.x)	20s
integration tests (ubuntu-20.04, 1.15.x)	43s
Linters (Static Analysis) for Go (ubuntu-20.04, 1.17.x)	22s
integration tests (ubuntu-20.04, 1.16.x)	45s
integration tests (ubuntu-20.04, 1.17.x)	51s
integration tests (macos-latest, 1.15.x)	3m 6s
integration tests (macos-latest, 1.16.x)	33s
integration tests (macos-latest, 1.17.x)	37s
integration tests (windows-latest, 1.15.x)	1m 14s
integration tests (windows-latest, 1.16.x)	1m 14s
integration tests (windows-latest, 1.17.x)	1m 14s
	11m 16s

Provide feedback