Always keep a minimum of 2 active dbs open

[BeniaminDrasovean]

Description of the reasoning behind the pull request (what feature was missing / how the problem was manifesting itself / what was the motive behind the refactoring)

• The pruning storer will keep only 3 db's open. When a snapshot takes longer than an epoch, it will close a db that is needed. To fix this case, always keep a minimum of 2 db's that are marked as active, opened.

Proposed Changes

• Modify minNumOfActiveDBsNecessary from 1 to 2

Testing procedure

• Add a time.Sleep() on Snapshot(), so that it will take more than 1 epoch, and check that the storer life was extended. After the snapshot is completed, verify that the correct db's are closed - (already tested this case)

[codecov-commenter]

Codecov Report

Merging #4343 (a833b56) into rc/2022-july (11e589f) will decrease coverage by 0.03%.
The diff coverage is n/a.

❗ Current head a833b56 differs from pull request most recent head b93697c. Consider uploading reports for the commit b93697c to get more accurate results

@@               Coverage Diff                @@
##           rc/2022-july    #4343      +/-   ##
================================================
- Coverage         73.74%   73.70%   -0.04%     
================================================
  Files               670      670              
  Lines             86388    86388              
================================================
- Hits              63707    63674      -33     
- Misses            17908    17941      +33     
  Partials           4773     4773              

Impacted Files	Coverage Δ
storage/pruning/triePruningStorer.go	69.36% <ø> (+1.80%)	⬆️
p2p/libp2p/netMessenger.go	76.10% <0.00%> (-3.92%)	⬇️
storage/txcache/txListBySenderMap.go	97.50% <0.00%> (-2.50%)	⬇️
...t/processor/peerAuthenticationRequestsProcessor.go	94.40% <0.00%> (-2.40%)	⬇️

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[popenta]

@@ Log scanner @@

snapshot-takes-too-long-fix

================================================================================

• Known Warnings 14
• New Warnings 6
• Known Errors 0
• New Errors 2
• Panics 0
  ================================================================================