fix(eventstore): precise decimal (#8527)

# Which Problems Are Solved

Float64 which was used for the event.Position field is [not precise in
go and gets rounded](https://github.com/golang/go/issues/47300). This
can lead to unprecies position tracking of events and therefore
projections especially on cockcoachdb as the position used there is a
big number.

example of a unprecies position:
exact: 1725257931223002628
float64: 1725257931223002624.000000

# How the Problems Are Solved

The float64 was replaced by
[github.com/jackc/pgx-shopspring-decimal](https://github.com/jackc/pgx-shopspring-decimal).

# Additional Changes

Correct behaviour of makefile for load tests.
Rename `latestSequence`-queries to `latestPosition`

internal/eventstore/repository/sql/crdb_test.go

@@ -4,6 +4,8 @@ import (
 	"database/sql"
 	"testing"
 
+	"github.com/shopspring/decimal"
+
 	"github.com/zitadel/zitadel/internal/eventstore"
 	"github.com/zitadel/zitadel/internal/eventstore/repository"
 )
@@ -312,7 +314,7 @@ func generateEvent(t *testing.T, aggregateID string, opts ...func(*repository.Ev
 		ResourceOwner: sql.NullString{String: "ro", Valid: true},
 		Typ:           "test.created",
 		Version:       "v1",
-		Pos:           42,
+		Pos:           decimal.NewFromInt(42),
 	}
 
 	for _, opt := range opts {