Fix calls to copy_bitmask to pass stream parameter

[davidwendt]

Description

Fixes a couple places where cudf::copy_bitmask was called instead of cudf::detail::copy_bitmask to pass the available stream (and mr) parameters.

Found while reviewing #14121
Reference: #14121 (comment)

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[davidwendt]

/merge