gh-129069: fix more thread safety issues in list

[kumaraditya303]

This PR fixes thread safety of list.reverse and slice assignment. Also changes stores to use release rather than relaxed as done in #142957.

• Issue: Race in concurrent list mutation and item retrieval #129069

[colesbury]

LGTM

I didn't measure any significant performance difference on fastbench on Apple M4.

Microbenchmarks for list.insert are a little slower on that same machine. Here's the benchmark (courtesy of ChatGPT):

https://gist.github.com/colesbury/b675c95d35f29ca9d5723b95396d48a8

Before:

begin n=100000 reps=1000 total=0.032732s avg=32.73µs/op middle n=100000 reps=1000 total=0.013755s avg=13.76µs/op end n=100000 reps=1000 total=0.000564s avg=0.56µs/op 

After:

begin n=100000 reps=1000 total=0.048336s avg=48.34µs/op middle n=100000 reps=1000 total=0.019781s avg=19.78µs/op end n=100000 reps=1000 total=0.000191s avg=0.19µs/op 

We could use ptr_wise_atomic_memmove in many of these places, which will probably be faster in the microbenchmarks, but I'm not sure it'll matter in real programs.