Feature Key file - ensure that the decoding works more robustly

[gargana]

If the Feature key file is encoded in Base-64 with line breaks, then extraction fails at the first line break.

[sourabh3b]

Possible solution - use regex pattern to check spaces in FeatureKeyFile field

In CFT we can update this section as : [to be tested]

  FeatureKeyFile:
    Description: Base64 encoding of the feature key file. This is the Aerospike key to use for this deployment. Keeping this blank works only for single node cluster.
    Type: String
    Default: ""
    ConstraintDescription: Must not have spaces in beginning or end
    AllowedPattern: '^[^\s].+[^\s]$'