Fix confirmations incremental dispatch

[peterbroadhurst]

~In PR chain with #93 ~
~Also contains commit from #96 ~
Rebased on main with 93/96 merged to aid review

I found that we were re-dispatching the whole set of confirmations each time, in the incremental case where NewFork: false

[codecov-commenter]

Codecov Report

Merging #94 (eb44387) into main (e6fe782) will decrease coverage by 0.04%.
The diff coverage is 98.81%.

@@            Coverage Diff             @@
##             main      #94      +/-   ##
==========================================
- Coverage   99.98%   99.94%   -0.04%     
==========================================
  Files          77       79       +2     
  Lines        5004     5153     +149     
==========================================
+ Hits         5003     5150     +147     
- Misses          1        3       +2     

Impacted Files	Coverage Δ
internal/persistence/persistence.go	100.00% <ø> (ø)
...nternal/persistence/postgres/transaction_writer.go	99.25% <90.47%> (-0.75%)	⬇️
internal/confirmations/confirmations.go	100.00% <100.00%> (ø)
...ternal/persistence/dbmigration/leveldb2postgres.go	100.00% <100.00%> (ø)
internal/persistence/dbmigration/migration.go	100.00% <100.00%> (ø)
...nternal/persistence/leveldb/leveldb_persistence.go	100.00% <100.00%> (ø)
internal/persistence/postgres/sqlpersistence.go	100.00% <100.00%> (ø)
internal/persistence/postgres/transactions.go	100.00% <100.00%> (ø)
pkg/txhandler/simple/policyloop.go	100.00% <100.00%> (ø)

[peterbroadhurst]

Rebased on main