CP-9229: Use new path for convert-legacy-stream

The previous path (.../legacy.py) was a symlink for backwards compatibility
with development and we would like to remove it before release.

Signed-off-by: Si Beaumont <simon.beaumont@citrix.com>
Merge pull request #1880 from simonjbeaumont/cp-9229-xs64bit

[xs64bit] CP-9229: Use new path for convert-legacy-stream