refactor: align error variant naming with airflow and hbase operators

Rename FailedToResolveResourceConfig to FailedToResolveConfig and
fix OPA error display string to match the convention used across
all three dereference/validate extraction PRs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: adwk67

rust/operator-binary/src/controller/dereference.rs

@@ -28,7 +28,7 @@ pub enum Error {
         source: stackable_operator::database_connections::Error,
     },
 
-    #[snafu(display("invalid OpaConfig"))]
+    #[snafu(display("invalid OPA configuration"))]
     InvalidOpaConfig {
         source: stackable_operator::commons::opa::Error,
     },

rust/operator-binary/src/controller/validate.rs

@@ -32,8 +32,8 @@ pub enum Error {
         source: stackable_operator::product_config_utils::Error,
     },
 
-    #[snafu(display("failed to resolve and merge resource config for role and role group"))]
-    FailedToResolveResourceConfig { source: crate::crd::Error },
+    #[snafu(display("failed to resolve and merge config for role and role group"))]
+    FailedToResolveConfig { source: crate::crd::Error },
 }
 
 /// Per-role configuration extracted during validation.
@@ -123,7 +123,7 @@ pub fn validate_cluster(
 
         let merged_config = hive
             .merged_config(&hive_role, &rolegroup)
-            .context(FailedToResolveResourceConfigSnafu)?;
+            .context(FailedToResolveConfigSnafu)?;
 
         group_configs.insert(
             rolegroup_name.clone(),