Fix bootcmd statements

Format bootcmd statements to be properly read by cloud init.

Changes:
	modified:   CERN-PROD_CLOUD.yaml
	modified:   CERN-PROD_CLOUD_MCORE.yaml
	modified:   GOOGLE_COMPUTE_ENGINE.yaml
	modified:   GRIDPP_CLOUD.yaml
	modified:   GRIDPP_MCORE.yaml
	modified:   IAAS.yaml
	modified:   IAAS_MCORE.yaml
	modified:   UKI-NORTHGRID-LANCS-HEP_CLOUD.yaml
	modified:   belle.yaml