[C++] Roll back to jemalloc stable-4 branch until performance issues in 5.2.x addressed

[asfimport]

New JIRA for changelog per ongoing thread in ARROW-6417

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

PRs and other links:

• GitHub Pull Request #5297

_{Note: This issue was originally created as ARROW-6478. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 5297
#5297