Do not reuse PersistentContextPtr instances

[szegedi]

What does this PR do?:
Removes caching/reuse of PersistentContextPtr instances.

Motivation:
This was always a speculative attempt to reduce native memory fragmentation. The standard library can be expected to do some of this itself, so we should not be doing this, especially since it is also removed in #255 and it seems to be causing issues (see #7355).

Additional Notes:
#255 also contains this, but we can roll it out as a quicker measure to try to eliminate the memory issue. An advantage of rolling this out separately is that #255 requires some changes in dd-trace-js too, while this as a standalone change does not.

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-02-09 12:25:49

Comparing candidate commit 2e18962 in PR branch szegedi/no-dead-list with baseline commit eb9eabd in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 92 metrics, 28 unstable metrics.

[github-actions]

Overall package size

Self size: 1.77 MB
Deduped: 2.16 MB
No deduping: 2.16 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | source-map | 0.7.6 | 185.63 kB | 185.63 kB | | pprof-format | 2.2.1 | 163.06 kB | 163.06 kB | | p-limit | 3.1.0 | 7.75 kB | 13.78 kB | | delay | 5.0.0 | 11.17 kB | 11.17 kB | | node-gyp-build | 3.9.0 | 8.81 kB | 8.81 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

[BridgeAR]

While we can try this, I do not believe this is the actual cause of the report