Normalize new line in WiX rules

This is a preparation to switch to WiX v4 (#894).

While there is an automated converter from WiX v3 rules to WiX v4 rules,
it normalizes every XML tag to a single line.

To minimize the diffs in the above process, this commit applies the same
normalization in prior.

This is a mechanical replacement. There must be no difference in the
final installer files.

#codehealth

PiperOrigin-RevId: 614834603