RFR: JDK-8264488: Improve warning for module names ending with digits

[Sebastian Stenzel]

Since this is a rather trivial change, I didn't start a new discussion, as I deem this sufficiently discussed [back in early 2021](https://mail.openjdk.org/pipermail/discuss/2021-March/005779.html).

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Commit messages:
 - missed to remove old message
 - update "module [...] avoid terminal digits" warning

Changes: https://git.openjdk.org/jdk/pull/14099/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14099&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8264488
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14099.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14099/head:pull/14099

PR: https://git.openjdk.org/jdk/pull/14099