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/database/cockroach/crdb.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"time"
 
+	pgxdecimal "github.com/jackc/pgx-shopspring-decimal"
+	"github.com/jackc/pgx/v5"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"github.com/jackc/pgx/v5/stdlib"
 	"github.com/mitchellh/mapstructure"
@@ -82,6 +84,11 @@ func (c *Config) Connect(useAdmin bool, pusherRatio, spoolerRatio float64, purpo
 		return nil, err
 	}
 
+	config.AfterConnect = func(ctx context.Context, conn *pgx.Conn) error {
+		pgxdecimal.Register(conn.TypeMap())
+		return nil
+	}
+
 	if connConfig.MaxOpenConns != 0 {
 		config.MaxConns = int32(connConfig.MaxOpenConns)
 	}