Use line comments instead of block comment for generated license headers

This makes it shorter.
1 job for !226 with work/simplifylicenseheader in 33 minutes and 12 seconds (queued for 33 minutes and 35 seconds)
latest detached
Status Job ID Name Coverage
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passed #91962
linux kf5-qt5 qt5.15

00:33:12

46.0%