[AGIPD] as_single_value instead of get_run_value

Using CONTROL source to read AGIPD conditions using as_single_value.

Description

Replacing get_run_value with as_single_value to read all conditions, except the bias_voltage.

To unify the method for reading the parameter conditions and not fail silently if there is a bug in the CONTROL values.

Except for the bias_voltage, which is known of wrong CONTROL values for AGIPD@HED.

How Has This Been Tested?

Relevant Documents (optional)

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

Reviewers

@calibration