Fix memory leak from repeated ProjDataInfo::clone() calls

[NikEfth]

This PR fixes a memory leak detected by AddressSanitizer in ScatterSimulation::set_template_proj_data_info.
The issue was caused by calling arg.clone() multiple times inside dynamic_cast expressions, leading to leaked heap allocations when the cast failed.

The fix:
• Calls clone() exactly once
• Transfers ownership safely using a smart pointer
• Preserves the existing runtime type checks for supported ProjDataInfo types

This change is purely a memory-safety fix and does not alter behaviour or interfaces.

Changes in this pull request

Testing performed

Related issues

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• I have performed a self-review of my code
• [] I have added docstrings/doxygen in line with the guidance in the developer guide
• [] I have implemented unit tests that cover any new or modified functionality (if applicable)
• The code builds and runs on my machine
• [] documentation/release_XXX.md has been updated with any functionality change (if applicable)

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• The content of this Pull Request (the Contribution) is intentionally submitted for inclusion in STIR (the Work) under the terms and conditions of the Apache-2.0 License.
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[NikEfth]

Based on CODACY suggestion I simplified a bit the set_template_proj_data_info() to use the shared_ptr