logproto: Add deprecated annotation to LegacySample and LegacyLabelPair (#5454)

* Add deprecated annotation to LegacySample and LegacyLabelPair

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

* Replace annotation with more generic docstring

Signed-off-by: Paschalis Tsilias <paschalis.tsilias@grafana.com>

pkg/logproto/logproto.pb.go

@@ -648,6 +648,7 @@ func (m *Sample) GetHash() uint64 {
 	return 0
 }
 
+// LegacySample exists for backwards compatibility reasons and is deprecated. Do not use.
 type LegacySample struct {
 	Value       float64 `protobuf:"fixed64,1,opt,name=value,proto3" json:"value,omitempty"`
 	TimestampMs int64   `protobuf:"varint,2,opt,name=timestamp_ms,json=timestampMs,proto3" json:"timestamp_ms,omitempty"`
@@ -1199,6 +1200,7 @@ func (m *LabelPair) GetValue() string {
 	return ""
 }
 
+// LegacyLabelPair exists for backwards compatibility reasons and is deprecated. Do not use.
 type LegacyLabelPair struct {
 	Name  []byte `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
 	Value []byte `protobuf:"bytes,2,opt,name=value,proto3" json:"value,omitempty"`

pkg/logproto/logproto.proto

@@ -97,6 +97,7 @@ message Sample {
   uint64 hash = 3 [(gogoproto.jsontag) = "hash"];
 }
 
+// LegacySample exists for backwards compatibility reasons and is deprecated. Do not use.
 message LegacySample {
   double value       = 1;
   int64 timestamp_ms = 2;
@@ -154,6 +155,7 @@ message LabelPair {
   string value = 2;
 }
 
+// LegacyLabelPair exists for backwards compatibility reasons and is deprecated. Do not use.
 message LegacyLabelPair {
   bytes name = 1;
   bytes value = 2;