rds/docdb: ParameterGroup in update loop bc of applyMethod

[wotolom]

What happened?

affecting RDS + DocDB: resources DBParameterGroup, DBClusterParametergroup

AWS seems to only consider changes to the field ApplyMethod, if the ParameterValue changes too.
This results in the controller constantly doing update calls.

I will provide a PR shortly.

How can we reproduce it?

example for DBParameterGroup:

apiVersion: rds.aws.crossplane.io/v1alpha1
kind: DBParameterGroup
metadata:
  name: example-dbparametergroup
spec:
  forProvider:
    region: us-east-1
    dbParameterGroupFamilySelector:
      engine: postgres
    description: "this applyMethod: immediate will not be set. AWS will only change it when parameterValue changes too "
    parameters:
      - applyMethod: immediate # immediate pending-reboot
        parameterName: rds.force_ssl
        parameterValue: "0"
  providerConfigRef:
    name: example

What environment did it happen in?

• Crossplane version: 1.11.1
• Provider-aws version: v0.38.0