COS role should use a targeted variable for IBM Cloud API Key

[durera]

The COS role uses IBMCOS_RESOURCEGROUP to allow COS specific setting of the group, but does not do the same for the API Key, this means that we are forced to use an over-priviledged API key for the COS integration ... it should work the same way:

• ibmcos_apikey
• ibmcos_resourcegroup

The MAS tekton piptlines and CLI will need matching updates too.