Improve TestingStrategy performance

[reneSchm]

Motivation / Current Behaviour

TestingStrategy uses somewhat expensive lookups to find entries, which can be replaced as we separated LocationType from LocationId.

Enhancement description

• Replace scheme storage, e.g. by two vectors (one for type, one for id).
• Update names, e.g. m_location_to_schemes_map is not a map.

Additional context

See discussion in PR #863, e.g. #863 (comment)

Checklist

• Attached labels, especially loc:: or model:: labels.
• Linked to project