Trim threadConfiguration to accept input surrounded with spaces

[pzygielo]

• space-prefixed core multiplier - is already supported - added support for space-suffix
• extended that behaviour for direct number of threads argument
• can be used in bizarre command line like mvn -T ' 1 ' or - why I'm here - with value indented in maven.config:

--threads
  1

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maven/CONTRIBUTING.md

Line 58 in 9ac23b0

+ Run all the tests with `mvn -Prun-its verify` to assure nothing else was accidentally broken.

[WARNING] The requested profile "run-its" could not be activated because it does not exist.

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• I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

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• Allow argument to --threads to be surrounded by spaces #11850

[slawekjaranowski]

@pzygielo we are starting on next minor version 3.10.x so new PR should be target to this branch, I will try to change a base branch ...

[pzygielo]

we are starting on next minor version 3.10.x so new PR should be target to this branch,

I missed that 3.10.x exists.

I will try to change a base branch ...

Thanks for checking!