chore: reduce FPs in decode-and-execute by removing file write and network connection sinks

[art1f1c3R]

Summary

Many false positives were being observed from decoded base64 data flowing through to file writes and network connections, both sinks in the obfuscation_decode-and-execute rule. This PR removes these sinks and finds little-to-no detection capability is lost and false positives are reduced.

Description of changes

File writes and network connection sinks are removed from obfuscation_decode-and-execute, and the tests are updated accordingly. This change was run on a set of malicious and trusted packages, and in comparison found 0 detections (0 false positives) for trusted packages, and only 2 less detections on the malicious packages.

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