distsqlpb: rename protos back to distsqlrun

The move of code to the `distsqlpb` package also inadvertently renamed
the actual protobuf service endpoints and messages, which represented an
accidental breaking change between 2.1 and 19.1 and would result in
errors in mixed clusters.

This commit reverts that change, restoring harmony for mixed-version
clusters.

Release note: None

pkg/sql/distsqlpb/api.proto

@@ -15,7 +15,10 @@
 // APIs for distributed SQL; see docs/RFCS/distributed_sql.md
 
 syntax = "proto2";
-package cockroach.sql.distsqlpb;
+// Beware! This package name must not be changed, even though it doesn't match
+// the Go package name, because it defines the Protobuf message names which
+// can't be changed without breaking backward compatibility.
+package cockroach.sql.distsqlrun;
 option go_package = "distsqlpb";
 
 import "gogoproto/gogo.proto";

pkg/sql/distsqlpb/data.proto

@@ -17,7 +17,10 @@
 // All the concepts here are "physical plan" concepts.
 
 syntax = "proto2";
-package cockroach.sql.distsqlpb;
+// Beware! This package name must not be changed, even though it doesn't match
+// the Go package name, because it defines the Protobuf message names which
+// can't be changed without breaking backward compatibility.
+package cockroach.sql.distsqlrun;
 option go_package = "distsqlpb";
 
 import "jobs/jobspb/jobs.proto";

pkg/sql/distsqlpb/processors.proto

@@ -17,7 +17,10 @@
 // All the concepts here are "physical plan" concepts.
 
 syntax = "proto2";
-package cockroach.sql.distsqlpb;
+// Beware! This package name must not be changed, even though it doesn't match
+// the Go package name, because it defines the Protobuf message names which
+// can't be changed without breaking backward compatibility.
+package cockroach.sql.distsqlrun;
 option go_package = "distsqlpb";
 
 import "jobs/jobspb/jobs.proto";

pkg/sql/trace_test.go

@@ -135,7 +135,7 @@ func TestTrace(t *testing.T) {
 			// Depending on whether the data is local or not, we may not see these
 			// spans.
 			optionalSpans: []string{
-				"/cockroach.sql.distsqlpb.DistSQL/SetupFlow",
+				"/cockroach.sql.distsqlrun.DistSQL/SetupFlow",
 				"noop",
 			},
 		},
@@ -201,7 +201,7 @@ func TestTrace(t *testing.T) {
 			// Depending on whether the data is local or not, we may not see these
 			// spans.
 			optionalSpans: []string{
-				"/cockroach.sql.distsqlpb.DistSQL/SetupFlow",
+				"/cockroach.sql.distsqlrun.DistSQL/SetupFlow",
 				"noop",
 			},
 		},