Conflict while trying to use hpa operator with appdynamics operator

[pliniogsnascimento]

Describe the bug
Hello! I'm currently using hpa operator for my resources and trying to implement appdynamics operator. When using custom metrics to hpa operator, it conflicts with other annotations defined in the deployment spec. It seems that the hpa operator tries to apply all annotations that it finds, instead of filtering specific annotations for HPA custom metrics.

Error log(deploy name removed for security reasons):

time="2021-05-24T15:22:19Z" level=error msg="Metric annotation for deployment <deploy_name> is invalid: APPD_DEPLOYMENT_INSTRUMENTATION_STATE"
time="2021-05-24T15:22:19Z" level=info msg="number of metrics: 0"

When this error happens, it only apply custom metrics in the hpa, breaking the builtin k8s metrics(cpu or memory).

Steps to reproduce the issue:

• Install Appdynamics operator and hpa operator in the same namespace.
• Configure custom metrics for hpa.

Expected behavior
HPA operator should apply hpa on custom metrics without trying to read a APPDYNAMICS annotation.

Additional context

• HPA Operator version: 0.2.0