verify: nicer failure message rendering in Prow

The "message" attribute is redundant. Adding line breaks ensures that the curly
brackets used by Prow are on separate lines.

Before:
    {Script Error ScriptError test/e2e/e2e.go:437:5: var `unused` is unused (unused)
    var unused = 1 // intentionally trigger a golangci-lint warning.
        ^}

After:
    {ScriptError
    test/e2e/e2e.go:437:5: var `unused` is unused (unused)
    var unused = 1 // intentionally trigger a golangci-lint warning.
        ^
    }

third_party/forked/shell2junit/sh2ju.sh

@@ -153,7 +153,9 @@ function juLog() {
           failureMsg="${errMsg}"
       fi
       failure="
-      <failure type=\"ScriptError\" message=\"Script Error\"><![CDATA[${failureMsg}]]></failure>
+      <failure type=\"ScriptError\"><![CDATA[
+${failureMsg}
+]]></failure>
   "
   fi
   ## testcase tag