Reduce repetition in "dbg.maps.count.after.map" test with alias

[kazarmy]

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• I've read the guidelines for contributing to this repository.
• I made sure to follow the project's coding style.
• I've documented every RZ_API function and struct this PR changes.
• I've added tests that prove my changes are effective (required for changes to RZ_API).
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Detailed description

This pr just reduces repetition in the "dbg.maps.count.after.map" test (part of the dbg_maps testfile) using an alias.

Test plan

All builds are green.

Closing issues

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