[Python] Remove workaround for CMake bug in manylinux

[asfimport]

The following issue should be fixed in CMake 3.18:
pypa/manylinux#484

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

PRs and other links:

• GitHub Pull Request #8500

_{Note: This issue was originally created as ARROW-10363. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 8500
#8500