perf: add tree processing cache to avoid redundant computations

[zyf265600]

Cache NewClassTree processing in NullnessNoInitAnnotatedTypeFactory to prevent duplicate type annotation calculations.

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Note

Adds a system property to disable the NonNull fast-path for new class sites and a jtreg benchmark to measure its performance impact.

• Nullness Checker:
  • Adds runtime toggle cf.skipNonnullFastPath in NullnessNoInitAnnotatedTypeFactory to optionally skip hasEffectiveAnnotation(NONNULL) fast-path.
  • Updates visitNewClass to short-circuit when fast-path is enabled; otherwise always add missing @NonNull.
• Performance Test:
  • Introduces checker/jtreg/nullness/perf/NewClassPerf.java to generate many new sites and time javac runs with/without the fast-path (-J-Dcf.skipNonnullFastPath=true).
  • Supports AB/BA/BOTH/SEPARATE protocols, warmups, and reports median/average deltas.

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