[C++] Switch back to latest jemalloc 5.x

[asfimport]

In ARROW-6478, we switched back to jemallox 4.x to fix a large performance regression in micro-benchmarks which appeared when bumping the vendored jemalloc version to 5.2.0.

Since then, the issue was discussed with the jemalloc maintainers and we found out that customizing some options allowed regaining all (or most) of the performance on micro-benchmarks with 5.2.x.

Reporter: Antoine Pitrou / @pitrou
Assignee: Antoine Pitrou / @pitrou

PRs and other links:

• GitHub Pull Request #5365

_{Note: This issue was originally created as ARROW-6549. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 5365
#5365