RFR: 8326948: Force English locale for timeout formatting

[Phil Race]

On Wed, 28 Feb 2024 12:20:04 GMT, Alexey Ivanov <aivanov at openjdk.org> wrote:

> If a test runs in non-English locale, the digits displayed in the timeout could be locale-specific, which may be confusing.
> 
> For example, in the Arabic locale `-Duser.language=ar`, the timeout is displayed like this:
> 
> Test timeout: ٠٠:٠٤:٥٨
> 
> The fix explicitly sets English locale for formatting, which ensures the timeout is always displayed with the Western Arabic numerals, see [Numerals in most popular systems](https://en.wikipedia.org/wiki/Numerical_digit#Numerals_in_most_popular_systems).

Marked as reviewed by prr (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/18042#pullrequestreview-1906999034