Fix round index timestamp

[miiu96]

Reasoning behind the pull request

• Fixes RoundInfo structure that is used in OutportDriver
• timestampMs field is not populated for the case when a block is not produced in a round

Pre-requisites

Based on the Contributing Guidelines the PR author and the reviewers must check the following requirements are met:

• was the PR targeted to the correct branch?
• if this is a larger feature that probably needs more than one PR, is there a feat branch created?
• if this is a feat branch merging, do all satellite projects have a proper tag inside go.mod?

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.57%. Comparing base (2451f5b) to head (2569090).
⚠️ Report is 3 commits behind head on feat/supernova-async-exec.

Files with missing lines	Patch %	Lines
consensus/spos/bls/v2/subroundStartRound.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@                    Coverage Diff                     @@
##           feat/supernova-async-exec    #7801   +/-   ##
==========================================================
  Coverage                      77.57%   77.57%           
==========================================================
  Files                            882      882           
  Lines                         123690   123698    +8     
==========================================================
+ Hits                           95954    95961    +7     
+ Misses                         21378    21377    -1     
- Partials                        6358     6360    +2     

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