BUGFIX: Throw explicit transaction has been marked for rollback only exception

[mhsdesign]

related #4970

improves the error message from totally obscured:

Failed to update and commit highest applied sequence number for subscriber "Neos\ContentGraph\DoctrineDbalAdapter\DoctrineDbalContentGraphProjection". Please run Neos\ContentRepository\Core\Infrastructure\DbalCheckpointStorage::setUp()

to partially obscure:

Failed to update and commit checkpoint for subscriber "Neos\ContentGraph\DoctrineDbalAdapter\DoctrineDbalContentGraphProjection" because the transaction has been marked for rollback only. See #4970

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• Code follows the PSR-2 coding style
• Tests have been created, run and adjusted as needed
• The PR is created against the lowest maintained branch
• Reviewer - PR Title is brief but complete and starts with FEATURE|TASK|BUGFIX
• Reviewer - The first section explains the change briefly for change-logs
• Reviewer - Breaking Changes are marked with !!! and have upgrade-instructions

[mhsdesign]

I will not attempt to fix #4970 actually in this pr. The current state and dx will already be improved with this hint.

[dlubitz]

LGTM

[mhsdesign]

Will merge this as this is a tiny debug developer improvement (no production behaviour change) and should not block our review capacity, which is currently low

[bwaidelich]

btw: since each apply() call is wrapped in a transaction anyways (for the checkpoint storage) I think we can remove all these nested transactions within.
I'll take care of that when working on the syncronous catchup implementation