Reduce transaction status and error constraint

[pasqu4le]

Motivation

Block invalidation can causes transactions to be refetched while previous internal transactions still exist, failing inserts/updates because of check constraints.

Because of this it is necessary to lift all checks on status and error, except the ones over block_hash (if NULL or not) and on status = 0 (or not).

Checklist for your PR

• I added an entry to CHANGELOG.md with this PR
• If I added new functionality, I added tests covering it.
• If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.
• I checked whether I should update the docs and did so if necessary

[coveralls]

Pull Request Test Coverage Report for Build 58cbc661-1c9a-4d30-95b4-134d736a887b

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.03%) to 81.111%

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Files with Coverage Reduction	New Missed Lines	%
apps/explorer/lib/explorer/chain/transaction.ex	1	84.0%

Totals
Change from base Build dbc300c4-e486-441e-ad9b-f378ec7fea2c:	-0.03%
Covered Lines:	5110
Relevant Lines:	6300

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💛 - Coveralls

[ayrat555]

tests are failing