Don't warn of script location in rosdoc2

[rkent]

Fixes #1051 which is concerned with WARNING: The script normalizer is installed in '/home/buildfarm/.local/bin'

@nuclearsandwich asked "it's also worth determining whether this warning is valid"

No, the warning is not valid. In the build step following the rosdoc2 install, the PATH is extended to include the warned-about directory.

This warning used to be repressed. That repression was removed in PR #1031, possibly inadvertently. This PR simply restores the original option.

[nuclearsandwich]

That repression was removed in PR #1031, possibly inadvertently.

Well I didn't document it, which, boo me, but I am sure I had some reason since I don't like to change things until I understand them. I normally look to my commit messages for concrete rationale but that PR and #1030 went through a few rounds of rebases and it looks like I lost the reason, but from the vague memory I have left and 6c398ef, I thought that the warning was caused by the way the source directory was being mounted and thus any new warning was for a different problem.