GH-126795: Increase the JIT side-exit threshold from 64 to 4096

[brandtbucher]

This should be covered by the NEWS entry in GH-126816. Looks like a ~0.5% speedup and ~0.5% memory savings, so nothing too dramatic there. Only 1/3 as many traces created though, with no change to the number of uops executed, so the memory and time we're saving does seem like it's completely wasted currently (stats).

I'm running benchmarks across all platforms now.

• Issue: Use a higher tier-up threshold for JIT code #126795

[brandtbucher]

Results across platforms. Very similar to GH-126816, in that it looks like the memory savings are more pronounced on AArch64 macOS and the performance impact is more pronounced on AArch64 Linux.

• aarch64-apple-darwin: 0.6% faster, 1.1% less memory
• aarch64-unknown-linux-gnu: 7.0% faster, 0.0% less memory
• x86_64-unknown-linux-gnu: 0.3-0.6% faster, 0.4-0.5% less memory
• x86_64-pc-windows-msvc: 0.3% slower
• i686-pc-windows-msvc: 1.1% faster

Another nice win for Arm, @diegorusso. :)