fix(net): modify getting blockid preference

[317787106]

What does this PR do?

• if num is bigger than head num, get blockid from khaosdb when generating syncblockchain message

Why are these changes required?

• if num is bigger than dynamic store's head, getting block from index store will fail

This PR has been tested by:

• Unit Tests
• Manual Testing

Follow up

Extra details

[codecov-commenter]

Codecov Report

Merging #5283 (cb3df71) into release_v4.7.2 (de45672) will decrease coverage by 0.01%.
The diff coverage is 50.00%.

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@@                 Coverage Diff                  @@
##             release_v4.7.2    #5283      +/-   ##
====================================================
- Coverage             60.86%   60.86%   -0.01%     
- Complexity             9197     9199       +2     
====================================================
  Files                   839      839              
  Lines                 49937    49940       +3     
  Branches               5562     5563       +1     
====================================================
  Hits                  30396    30396              
- Misses                17158    17162       +4     
+ Partials               2383     2382       -1     

Impacted Files	Coverage Δ
...va/org/tron/core/net/service/sync/SyncService.java	57.78% <50.00%> (-0.89%)	⬇️

... and 7 files with indirect coverage changes

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