[Dev] Update release scripts to use default branch

[asfimport]

Reporter: Neal Richardson / @nealrichardson
Assignee: Fiona La / @lafiona

PRs and other links:

• GitHub Pull Request #12489

_{Note: This issue was originally created as ARROW-15692. Please see the migration documentation for further details.}

[asfimport]

Kouhei Sutou / @kou:
Issue resolved by pull request 12489
#12489