refactor(prometheusreceiver): Moves targetallocator package to internal. (#44108)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Move `targetallocator` package to `internal/targetallocator` to prevent
external usage.

The targetallocator package was previously exposed as a public API, but
it was never intended for external consumption. This change moves the
package under the `internal/` directory.

<!-- Issue number (e.g. #1234) or full URL to issue, if applicable. -->
#### Link to tracking issue
Fixes #43996 

<!--Describe what testing was performed and which tests were added.-->
#### Testing

- [x] All existing tests pass
- [x] Build succeeds: go build ./...

<!--Describe the documentation added.-->
#### Documentation

No documentation changes needed as this package was not documented for
external use.

<!--Please delete paragraphs that you did not use before submitting.-->

Author: Angith

receiver/prometheusreceiver/config.go

@@ -22,7 +22,7 @@ import (
 	"go.opentelemetry.io/collector/config/configoptional"
 	"go.opentelemetry.io/collector/confmap"
 
-	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 )
 
 // Config defines configuration for Prometheus receiver.

receiver/prometheusreceiver/targetallocator/config.go renamed to receiver/prometheusreceiver/internal/targetallocator/config.go

@@ -1,7 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 
 import (
 	"encoding/base64"

receiver/prometheusreceiver/targetallocator/config_test.go renamed to receiver/prometheusreceiver/internal/targetallocator/config_test.go

@@ -1,7 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 
 import (
 	"path/filepath"

receiver/prometheusreceiver/targetallocator/manager.go renamed to receiver/prometheusreceiver/internal/targetallocator/manager.go

@@ -1,7 +1,7 @@
 // Copyright The OpenTelemetry Authors
 // SPDX-License-Identifier: Apache-2.0
 
-package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+package targetallocator // import "github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 
 import (
 	"bytes"

receiver/prometheusreceiver/targetallocator/manager_test.go renamed to receiver/prometheusreceiver/internal/targetallocator/manager_test.go

@@ -46,7 +46,7 @@ import (
 	"golang.org/x/net/netutil"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal"
-	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 )
 
 const (

receiver/prometheusreceiver/targetallocator/testdata/config.yaml renamed to receiver/prometheusreceiver/internal/targetallocator/testdata/config.yaml

@@ -31,7 +31,7 @@ import (
 	"go.uber.org/zap/zapcore"
 
 	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/metadata"
-	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/targetallocator"
+	"github.com/open-telemetry/opentelemetry-collector-contrib/receiver/prometheusreceiver/internal/targetallocator"
 )
 
 const exportedMetrics = `