[Packaging] Enable Flight in Conda packages

[asfimport]

We should build Conda packages with Flight enabled.

Reporter: David Li / @lidavidm
Assignee: David Li / @lidavidm

PRs and other links:

• GitHub Pull Request #4473

_{Note: This issue was originally created as ARROW-5511. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
Issue resolved by pull request 4473
#4473