<i18n dev> RFR: 8298047: Remove all non-significant trailing whitespace from properties files [v2]

[Magnus Ihse Bursie]

> [JDK-8295729](https://bugs.openjdk.org/browse/JDK-8295729) was created in an attempt to remove all trailing whitespace from properties files, and enable a jcheck verification that they did not come back, similar to other source code. It turned out that this was not so simple, however, since trailing whitespace in values is actually significant in properties files.
> 
> To address this, I have opened four bugs on different component teams to either remove the trailing significant whitespace (if it is there erroneously), or convert it to the unicode sequence `\u0020`: [JDK-8298042](https://bugs.openjdk.org/browse/JDK-8298042), [JDK-8298044](https://bugs.openjdk.org/browse/JDK-8298044), [JDK-8298045](https://bugs.openjdk.org/browse/JDK-8298045) and [JDK-8298046](https://bugs.openjdk.org/browse/JDK-8298046).
> 
> That leaves all the other trailing spaces, in blank lines and in the end of comments. These serve no purpose and should just be removed, and is what this issue concerns.
> 
> When this and the four "significant whitespace" bugs are all finally integrated, we can finally turn on the verification in jcheck for properties files as well.
> 
> The changes in this PR is based on [JDK-8295729](https://bugs.openjdk.org/browse/JDK-8295729), in #10792. I have restored all the "delete trailing whitespace" changes, except for those with significance. These changes were in turned created by  running `find . -type f -iname "*.properties" | xargs gsed -i -e 's/[ \t]*$//'`.

Magnus Ihse Bursie has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Merge branch 'master' into properties-eol-clean-safe
 - 8298047: Remove all non-significant trailing whitespace from properties files

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Changes: https://git.openjdk.org/jdk/pull/11491/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11491&range=01
  Stats: 693 lines in 264 files changed: 0 ins; 0 del; 693 mod
  Patch: https://git.openjdk.org/jdk/pull/11491.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11491/head:pull/11491

PR: https://git.openjdk.org/jdk/pull/11491