Use opm time_vector

[alifbe]

We need to revert PR #722 when next OPM is release (> 2024.4)

[larsevj]

Is this actionable? A bit unclear what the original issue was, and if it is solved in the current opm version 2025.4 ?

[alifbe]

Unfortunately not. I see that the required PR is not yet merged. OPM/opm-common#4165

The issue is related to changes in OPM 2024.4 which make the parsing of schedule file more strict. Unless TimeVector in OPM is updated (so that it's less strict), we need to keep using our own version.