Memory leaks fixed in profiling, SCA, and periodic timers

Bug Fixes

• internal: Fixed an issue that could have caused some timers, like the one responsible for Symbol Database uploads, to fire repeatedly after the first execution.

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• internal: This fix resolves a memory leak where reference cycles through PeriodicThread callbacks were invisible to Python's cyclic garbage collector and could accumulate when threads used bound methods as targets.

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• profiling: Fixes a memory leak in native frame tracking caused by unbounded native call-site metadata growth.

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• SCA: This fix resolves an issue where unresolved runtime reachability targets could accumulate across Software Composition Analysis updates, causing resident memory usage to grow over time.