[C++] Whitelist benchmarks candidates for regression checks

[asfimport]

Rename all benchmarks candidate for regression with the Regression prefix.

Reporter: Francois Saint-Jacques / @fsaintjacques
Assignee: Francois Saint-Jacques / @fsaintjacques

Related issues:

• [Benchmarking] Support for on-demand and automated benchmarks (blocks)

PRs and other links:

• GitHub Pull Request #4285

_{Note: This issue was originally created as ARROW-5269. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 4285
#4285