fix: actions v2beta with api design for GA (#10303)

# Which Problems Are Solved

Actions v2beta API does not adhere to the [API
design](https://github.com/zitadel/zitadel/blob/main/API_DESIGN.md)
fully.

# How the Problems Are Solved

- Correct body usage for ListExecutions
- Correct REST path for ListTargets and ListExecutions
- Correct attribute names for ListTargetsResponse and
ListExecutionsResponse

# Additional Changes

- Remove unused object import.

# Additional Context

Closes #10138

---------

Co-authored-by: Marco A. <marco@zitadel.com>

proto/zitadel/action/v2beta/action_service.proto

@@ -290,7 +290,7 @@ service ActionService {
   //   - `actions`
   rpc ListTargets (ListTargetsRequest) returns (ListTargetsResponse) {
     option (google.api.http) = {
-      post: "/v2beta/actions/targets/_search",
+      post: "/v2beta/actions/targets/search",
       body: "*"
     };
 
@@ -372,7 +372,8 @@ service ActionService {
   //   - `actions`
   rpc ListExecutions (ListExecutionsRequest) returns (ListExecutionsResponse) {
     option (google.api.http) = {
-      post: "/v2beta/actions/executions/_search"
+      post: "/v2beta/actions/executions/search"
+      body: "*"
     };
 
     option (zitadel.protoc_gen_zitadel.v2.options) = {
@@ -663,8 +664,9 @@ message ListTargetsRequest {
 }
 
 message ListTargetsResponse {
+  reserved 'result';
   zitadel.filter.v2beta.PaginationResponse pagination = 1;
-  repeated Target result = 2;
+  repeated Target targets = 2;
 }
 
 message SetExecutionRequest {
@@ -703,8 +705,9 @@ message ListExecutionsRequest {
 }
 
 message ListExecutionsResponse {
+  reserved 'result';
   zitadel.filter.v2beta.PaginationResponse pagination = 1;
-  repeated Execution result = 2;
+  repeated Execution executions = 2;
 }
 
 message ListExecutionFunctionsRequest{}

proto/zitadel/action/v2beta/execution.proto

@@ -11,7 +11,6 @@ import "validate/validate.proto";
 import "zitadel/protoc_gen_zitadel/v2/options.proto";
 
 import "google/protobuf/timestamp.proto";
-import "zitadel/object/v3alpha/object.proto";
 
 option go_package = "github.com/zitadel/zitadel/pkg/grpc/action/v2beta;action";