[IMP] hr_holidays: improve leave request form display of duration
[IMP] hr_holidays: improve leave request form display of duration

Purpose: better display duration. Label for hours / days is not very user
friendly when displayed left compared to the value. In this commit we
move the unit display right of the value and correctly display choices
related to the leave request date options.

Part of the spec: https://drive.google.com/file/d/1XQtw5ZiAebycXbeHmfbDYYwrFTRmkBNU/view

This commit is linked to task ID 1871812 and PR #26180.

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