perf(actionsv2): execution target router (#10564)

# Which Problems Are Solved

The event execution system currently uses a projection handler that
subscribes to and processes all events for all instances. This creates a
high static cost because the system over-fetches event data, handling
many events that are not needed by most instances. This inefficiency is
also reflected in high "rows returned" metrics in the database.

# How the Problems Are Solved

Eliminate the use of a project handler. Instead, events for which
"execution targets" are defined, are directly pushed to the queue by the
eventstore. A Router is populated in the Instance object in the authz
middleware.

- By joining the execution targets to the instance, no additional
queries are needed anymore.
- As part of the instance object, execution targets are now cached as
well.
- Events are queued within the same transaction, giving transactional
guarantees on delivery.
- Uses the "insert many fast` variant of River. Multiple jobs are queued
in a single round-trip to the database.
- Fix compatibility with PostgreSQL 15

# Additional Changes

- The signing key was stored as plain-text in the river job payload in
the DB. This violated our [Secrets
Storage](https://zitadel.com/docs/concepts/architecture/secrets#secrets-storage)
principle. This change removed the field and only uses the encrypted
version of the signing key.
- Fixed the target ordering from descending to ascending.
- Some minor linter warnings on the use of `io.WriteString()`.

# Additional Context

- Introduced in https://github.com/zitadel/zitadel/pull/9249
- Closes https://github.com/zitadel/zitadel/issues/10553
- Closes https://github.com/zitadel/zitadel/issues/9832
- Closes https://github.com/zitadel/zitadel/issues/10372
- Closes https://github.com/zitadel/zitadel/issues/10492

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>
(cherry picked from commit a9ebc06c77)

internal/query/generic.go

@@ -5,6 +5,7 @@ import (
 	"database/sql"
 
 	sq "github.com/Masterminds/squirrel"
+	"github.com/zitadel/logging"
 
 	"github.com/zitadel/zitadel/internal/api/authz"
 	"github.com/zitadel/zitadel/internal/database"
@@ -24,6 +25,7 @@ func genericRowsQuery[R any](
 
 	stmt, args, err := query.ToSql()
 	if err != nil {
+		logging.OnError(err).Warn("query: invalid request")
 		return rnil, zerrors.ThrowInvalidArgument(err, "QUERY-05wf2q36ji", "Errors.Query.InvalidRequest")
 	}
 	err = client.QueryContext(ctx, func(rows *sql.Rows) error {
@@ -31,6 +33,7 @@ func genericRowsQuery[R any](
 		return err
 	}, stmt, args...)
 	if err != nil {
+		logging.OnError(err).Error("query: internal error")
 		return rnil, zerrors.ThrowInternal(err, "QUERY-y2u7vctrha", "Errors.Internal")
 	}
 	return resp, err
@@ -50,6 +53,7 @@ func genericRowsQueryWithState[R Stateful](
 	}
 	state, err := latestState(ctx, client, projection)
 	if err != nil {
+		logging.OnError(err).Error("query: latest state")
 		return rnil, err
 	}
 	resp.SetState(state)