[R] Test quarter-year parser with trailing zeroes in the year when values are numeric

In ARROW-18285 we removed some tests that had trailing zeroes in numeric inputs (e.g., `1.2020`). This used to work in lubridate but support was removed (probably not on purpose; follow-up with lubridate is here: https://github.com/tidyverse/lubridate/issues/1091 ). The behaviour still works in arrow but because our test tests "roundtrip" behaviour it was causing a lot of CI to fail so that specific corner case was removed. When this is resolved in lubridate, we could consider re-adding those cases.

**Reporter**: [Dewey Dunnington](https://issues.apache.org/jira/browse/ARROW-18304) / @paleolimbot

_{**Note**: *This issue was originally created as [ARROW-18304](https://issues.apache.org/jira/browse/ARROW-18304). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

Start by reviewing the removed numeric-input cases from ARROW-18285 and the related lubridate issue 1091. Check whether lubridate has restored support for values such as `1.2020`; when it has, re-add the quarter-year roundtrip cases and confirm that CI no longer fails.

Written by the indexing model from the issue text.