Refine `mode: production` diagnostic output (#2236)

## Changes

This refines the `mode: production` diagnostic output now that the
`Detail` property is rendered as output. This is a follow-up to
https://github.com/databricks/cli/pull/1712.

bundle/config/mutator/process_target_mode.go

@@ -144,8 +144,11 @@ func validateProductionMode(ctx context.Context, b *bundle.Bundle, isPrincipalUs
 
 	// We need to verify that there is only a single deployment of the current target.
 	// The best way to enforce this is to explicitly set root_path.
-	advice := fmt.Sprintf(
+	advice := "set 'workspace.root_path' to make sure only one copy is deployed"
-		"set 'workspace.root_path' to make sure only one copy is deployed. A common practice is to use a username or principal name in this path, i.e. root_path: /Workspace/Users/%s/.bundle/${bundle.name}/${bundle.target}",
+	adviceDetail := fmt.Sprintf(
+		"A common practice is to use a username or principal name in this path, i.e. use\n"+
+			"\n"+
+			"  root_path: /Workspace/Users/%s/.bundle/${bundle.name}/${bundle.target}",
 		b.Config.Workspace.CurrentUser.UserName,
 	)
 	if !isExplicitRootSet(b) {
@@ -154,9 +157,21 @@ func validateProductionMode(ctx context.Context, b *bundle.Bundle, isPrincipalUs
 			// and neither is setting a principal.
 			// We only show a warning for these cases since we didn't historically
 			// report an error for them.
-			return diag.Recommendationf("target with 'mode: production' should %s", advice)
+			return diag.Diagnostics{
+				{
+					Severity: diag.Recommendation,
+					Summary:  "target with 'mode: production' should " + advice,
+					Detail:   adviceDetail,
+				},
+			}
+		}
+		return diag.Diagnostics{
+			{
+				Severity: diag.Error,
+				Summary:  "target with 'mode: production' must " + advice,
+				Detail:   adviceDetail,
+			},
 		}
-		return diag.Errorf("target with 'mode: production' must %s", advice)
 	}
 	return nil
 }

bundle/config/mutator/process_target_mode_test.go

@@ -329,7 +329,7 @@ func TestProcessTargetModeProduction(t *testing.T) {
 	b := mockBundle(config.Production)
 
 	diags := validateProductionMode(context.Background(), b, false)
-	require.ErrorContains(t, diags.Error(), "target with 'mode: production' must set 'workspace.root_path' to make sure only one copy is deployed. A common practice is to use a username or principal name in this path, i.e. root_path: /Workspace/Users/lennart@company.com/.bundle/${bundle.name}/${bundle.target}")
+	assert.ErrorContains(t, diags.Error(), "A common practice is to use a username or principal name in this path, i.e. use\n\n  root_path: /Workspace/Users/lennart@company.com/.bundle/${bundle.name}/${bundle.target}")
 
 	b.Config.Workspace.StatePath = "/Shared/.bundle/x/y/state"
 	b.Config.Workspace.ArtifactPath = "/Shared/.bundle/x/y/artifacts"
@@ -337,7 +337,7 @@ func TestProcessTargetModeProduction(t *testing.T) {
 	b.Config.Workspace.ResourcePath = "/Shared/.bundle/x/y/resources"
 
 	diags = validateProductionMode(context.Background(), b, false)
-	require.ErrorContains(t, diags.Error(), "target with 'mode: production' must set 'workspace.root_path' to make sure only one copy is deployed. A common practice is to use a username or principal name in this path, i.e. root_path: /Workspace/Users/lennart@company.com/.bundle/${bundle.name}/${bundle.target}")
+	assert.ErrorContains(t, diags.Error(), "A common practice is to use a username or principal name in this path, i.e. use\n\n  root_path: /Workspace/Users/lennart@company.com/.bundle/${bundle.name}/${bundle.target}")
 
 	permissions := []resources.Permission{
 		{