clean up prepared transactions in (*DB).Close

[jchappelow]

Not just regular transactions. This avoids annoying orphaned prepared transactions in the case where a bug results in closing the DB when there is an active transaction.

[jchappelow]

Verification:

2024-12-06 14:38:12.228 [INF] NODE: Node stopped.
2024-12-06 14:38:12.228 [INF] KWILD: Closing server resources...
2024-12-06 14:38:12.228 [INF] KWILD: Closing Eventstore DB
2024-12-06 14:38:12.228 [INF] KWILD: closing blockstore
2024-12-06 14:38:12.282 [INF] KWILD: closing main DB
2024-12-06 14:38:12.283 [WRN] PG: Rolling back PREPARED transaction XW6P1Sk1z8
panic: Closed the DB with an active transaction!

goroutine 1 [running]:
github.com/kwilteam/kwil-db/node/pg.(*DB).Close(0xc0003bc3c0)
	/home/jon/kwil/git/kwil-db/node/pg/db.go:296 +0x278
github.com/kwilteam/kwil-db/app/node.(*closeFuncs).addCloser.func1()
	/home/jon/kwil/git/kwil-db/app/node/deps.go:94 +0x43
github.com/kwilteam/kwil-db/app/node.(*closeFuncs).closeAll(0xc000016e58?)
	/home/jon/kwil/git/kwil-db/app/node/deps.go:102 +0x6b
github.com/kwilteam/kwil-db/app/node.(*server).Start.func1()
	/home/jon/kwil/git/kwil-db/app/node/node.go:120 +0xe7
github.com/kwilteam/kwil-db/app/node.(*server).Start(0xc000778180, {0x1f668e0, 0xc0006228c0})
	/home/jon/kwil/git/kwil-db/app/node/node.go:183 +0x41c
github.com/kwilteam/kwil-db/app/node.runNode({0x1f668e0, 0xc0006228c0}, {0x7ffcd92b10b0, 0xe}, 0xc0000e5340)
	/home/jon/kwil/git/kwil-db/app/node/node.go:110 +0xd5c
github.com/kwilteam/kwil-db/app/node.StartCmd.func1(0xc00023ec08, {0xc000150740?, 0x0?, 0x2?})
	/home/jon/kwil/git/kwil-db/app/node/start.go:43 +0xfc