UE: update pdcch config only after mib read
- In MR !3929, this change was done to call update_pdcch_config if mac
configuration is changed.
- Observed that the issue related to RAR after handover if SSB position changes
occurs also in develop 2026_w10 where MR !3929 is merged.
- update_pdcch_config should be done only after sync obtained.
- this fix is similar to the fix in initial commits of MR !3929