all: update golang/x/ext and fix slice sorting fallout (#27909)

The Go authors updated golang/x/ext to change the function signature of the slices sort method. 
It's an entire shitshow now because x/ext is not tagged, so everyone's codebase just 
picked a new version that some other dep depends on, causing our code to fail building.

This PR updates the dep on our code too and does all the refactorings to follow upstream...

ethdb/dbtest/testsuite.go

@@ -527,7 +527,7 @@ func makeDataset(size, ksize, vsize int, order bool) ([][]byte, [][]byte) {
 		vals = append(vals, randBytes(vsize))
 	}
 	if order {
-		slices.SortFunc(keys, func(a, b []byte) bool { return bytes.Compare(a, b) < 0 })
+		slices.SortFunc(keys, func(a, b []byte) int { return bytes.Compare(a, b) })
 	}
 	return keys, vals
 }