spack.yaml: remove comments copied from the template #335

Job	Run time
Closed / Setup	5s
Comment	-1s
CI	-1s
Closed / Undeploy Prereleases Matching access-test-pr55-* / Validate Inputs	2s
Closed / Undeploy Prereleases Matching access-test-pr55-* / Undeploy access-test-pr55-* from Gadi Prerelease	3m 15s
	3m 20s

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