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/query/current_state_test.go

@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"regexp"
 	"testing"
+
+	"github.com/shopspring/decimal"
 )
 
 var (
@@ -87,7 +89,7 @@ func Test_CurrentSequencesPrepares(t *testing.T) {
 						State: State{
 							EventCreatedAt: testNow,
 							LastRun:        testNow,
-							Position:       20211108,
+							Position:       decimal.NewFromInt(20211108),
 							AggregateID:    "agg-id",
 							AggregateType:  "agg-type",
 							Sequence:       20211108,
@@ -134,7 +136,7 @@ func Test_CurrentSequencesPrepares(t *testing.T) {
 						ProjectionName: "projection-name",
 						State: State{
 							EventCreatedAt: testNow,
-							Position:       20211108,
+							Position:       decimal.NewFromInt(20211108),
 							LastRun:        testNow,
 							AggregateID:    "agg-id",
 							AggregateType:  "agg-type",
@@ -145,7 +147,7 @@ func Test_CurrentSequencesPrepares(t *testing.T) {
 						ProjectionName: "projection-name2",
 						State: State{
 							EventCreatedAt: testNow,
-							Position:       20211108,
+							Position:       decimal.NewFromInt(20211108),
 							LastRun:        testNow,
 							AggregateID:    "agg-id",
 							AggregateType:  "agg-type",