[debugger] Fixed timestamp format (ms width)
[debugger] Fixed timestamp format (ms width)

Unfixed ms width ("%d") leads to vary digits from 1 to 6.
Now the width is statically 6 digits, filled with leading zeros ("%06d")

REVIEW: 128809

KDE/ktp-common-internals,KDE/ktp-common-internals,KDE/ktp-common-internals