Change default for logs_per_block & max_logs_kept columns from NULL to 0

[reductionista]

During PR review of #11949, we decided to change the types of [ max_logs_kept / MaxLogsKept ]
and[ logs_per_block / LogsPerBlock ] from [ NUMERIC / *big.Int ] to [ BIGINT / uint64 ]. I intended the default value to be 0 now instead of NULL,
but forgot to add the corresponding NOT NULL DEFAULT 0 clause to these columns in the db schema

type Filter struct {
...
	MaxLogsKept  uint64             // maximum number of logs to retain ( 0 = unlimited )
	LogsPerBlock uint64             // rate limit ( maximum # of logs per block, 0 = unlimited )
}

[github-actions]

I see that you haven't updated any CHANGELOG files. Would it make sense to do so?

[cl-sonarqube-production]

Quality Gate passed

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