remote_execution_effective_user is not honored as host parameter in Satellite 6

STEPS TO REPRODUCE:
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1. Add the remote_execution_effective_user param on host in the parameter tab of the host.

2. Try to run a job

3. The effective user used is still the one defined in Administer -> Settings -> rex

Expectations: remote_execution_effective_user mentioned on the host as host param should be used.

This will affect users who would want to use a different effective user. For eg: oracle db servers where commands need to be run as oracle user and not root.