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/search_query.go

@@ -5,6 +5,8 @@ import (
 	"database/sql"
 	"time"
 
+	"github.com/shopspring/decimal"
+
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/zerrors"
 )
@@ -23,7 +25,7 @@ type SearchQueryBuilder struct {
 	queries               []*SearchQuery
 	tx                    *sql.Tx
 	allowTimeTravel       bool
-	positionAfter         float64
+	positionGreaterEqual  decimal.Decimal
 	awaitOpenTransactions bool
 	creationDateAfter     time.Time
 	creationDateBefore    time.Time
@@ -74,8 +76,8 @@ func (b *SearchQueryBuilder) GetAllowTimeTravel() bool {
 	return b.allowTimeTravel
 }
 
-func (b SearchQueryBuilder) GetPositionAfter() float64 {
-	return b.positionAfter
+func (b SearchQueryBuilder) GetPositionAfter() decimal.Decimal {
+	return b.positionGreaterEqual
 }
 
 func (b SearchQueryBuilder) GetAwaitOpenTransactions() bool {
@@ -131,8 +133,8 @@ type Columns int8
 const (
 	//ColumnsEvent represents all fields of an event
 	ColumnsEvent = iota + 1
-	// ColumnsMaxSequence represents the latest sequence of the filtered events
-	ColumnsMaxSequence
+	// ColumnsMaxPosition represents the latest sequence of the filtered events
+	ColumnsMaxPosition
 	// ColumnsInstanceIDs represents the instance ids of the filtered events
 	ColumnsInstanceIDs
 
@@ -267,8 +269,8 @@ func (builder *SearchQueryBuilder) AllowTimeTravel() *SearchQueryBuilder {
 }
 
 // PositionAfter filters for events which happened after the specified time
-func (builder *SearchQueryBuilder) PositionAfter(position float64) *SearchQueryBuilder {
-	builder.positionAfter = position
+func (builder *SearchQueryBuilder) PositionGreaterEqual(position decimal.Decimal) *SearchQueryBuilder {
+	builder.positionGreaterEqual = position
 	return builder
 }