refactor: clean up variables and messages #900

Job	Run time
test-auth	2m 14s
matrix-prep-bazelversion	2s
test (ubuntu-latest, 6.2.0, ., true)	2m 52s
test (ubuntu-latest, 6.2.0, ., false)	3m 3s
test (ubuntu-latest, 6.2.0, e2e/custom_registry, false)	2m 9s
test (ubuntu-latest, 6.2.0, e2e/wasm, false)	1m 17s
test (ubuntu-latest, 6.2.0, e2e/smoke, true)	53s
test (ubuntu-latest, 6.2.0, e2e/smoke, false)	1m 3s
test (ubuntu-latest, 6.2.0, e2e/crane_as_registry, true)	22s
test (ubuntu-latest, 6.2.0, e2e/crane_as_registry, false)	19s
test (ubuntu-latest, 5.3.2, ., false)	2m 52s
test (ubuntu-latest, 5.3.2, e2e/custom_registry, false)	2m 7s
test (ubuntu-latest, 5.3.2, e2e/wasm, false)	1m 26s
test (ubuntu-latest, 5.3.2, e2e/smoke, false)	49s
test (ubuntu-latest, 5.3.2, e2e/crane_as_registry, false)	40s
	22m 8s

Provide feedback