Remove redundant string concatenations when unwrapping lines

[dpursehouse]

In code that has string concatenation wrapped on multiple lines, the formatter should remove any redundant concatenations when unwrapping the line.

See this reformatting change on the gerrit project for example:

The original code:

      throw new IllegalStateException(String.format(
          "SubmitRuleEvaluator.evaluate for change %s " +
          "returned empty list for %s in %s",
          cd.getId(),
          patchSet.getId(),
          cd.change().getProject().get()));

And after reformatting:

    throw new IllegalStateException(
          String.format(
              "SubmitRuleEvaluator.evaluate for change %s " + "returned empty list for %s in %s",
              cd.getId(), patchSet.getId(), cd.change().getProject().get()));

The first parameter to String.format now has a redundant concatenation, and would be better as:

          String.format(
              "SubmitRuleEvaluator.evaluate for change %s returned empty list for %s in %s",
              cd.getId(), patchSet.getId(), cd.change().getProject().get()));