Make only-mvnw.cmd pick the first matching extracted directory (#442)

[tanvir-ux]

When the extracted archive directory name does not match the archive filename, both wrapper scripts scan for a subdirectory that contains bin/$MVN_CMD. Unix only-mvnw already stops at the first match. only-mvnw.cmd used ForEach-Object with no early exit, so the last match won.

I changed the Windows scan to a foreach with break so both scripts pick the same directory from the same archive.

Fixes #442

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This is a few-line script change in only-mvnw.cmd. I did not add a PowerShell test harness.

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