[FIXED JENKINS-22568] Subversion polling does not work with parameters.

Currently subversion polling does not work with parameters. This code changes polls using the _DEFAULT_ option. If there is a choice parameter, it will choose the _FIRST_ option. This will also expand anything that is `$VAL` or `${VAL}`.
Avoid making formatting changes in PRs or really any commits. It makes diffs harder to read, `git blame` useless, and merges and cherry picks more likely to end in spurious merge conflicts.