feat(events): adjust indexes in event index db to match query patterns

[rvagg]

Introduces a v4 migration that just adjusts indexes.

Copies some improvements from #11723

Closes: #11909

/cc @i-norden

[rvagg]

Updated my calibnet node with master:

{"level":"info","ts":"2024-04-29T14:02:24.696+1000","logger":"filter","caller":"filter/index.go:432","msg":"Upgrading event index from version 2 to version 3"}
{"level":"info","ts":"2024-04-29T14:02:25.046+1000","logger":"filter","caller":"filter/index.go:313","msg":"Successfully migrated event index from version 2 to version 3 in 349.827948ms"}
{"level":"info","ts":"2024-04-29T14:02:25.046+1000","logger":"filter","caller":"filter/index.go:442","msg":"Upgrading event index from version 3 to version 4"}
{"level":"info","ts":"2024-04-29T14:02:25.046+1000","logger":"filter","caller":"filter/index.go:374","msg":"Performing DB vacuum and wal checkpointing to free up space after the migration"}
{"level":"info","ts":"2024-04-29T14:02:32.881+1000","logger":"filter","caller":"filter/index.go:366","msg":"Successfully migrated events to version 3 in 7.835114071s"}

fixing that last message in #11937, my bad in this PR, and I was being so careful making everything consistent!