Construct the full custom condition including the prefix

Condition contains the change prefix + " is " + the actual value
that should be true.

Plugins only provide the latter part and we should prefix it
with prefix to form the full condition.

Verified it works locally.

Release-Notes: skip
Bug: Google b/482366559
Change-Id: Iab564c1cbb6497a5062d551042ae106941d6862b

polygerrit-ui/app/models/flows/flows-model.ts

diff --git a/polygerrit-ui/app/models/flows/flows-model.ts b/polygerrit-ui/app/models/flows/flows-model.ts
index f085fb6..300a1b7 100644
--- a/polygerrit-ui/app/models/flows/flows-model.ts
+++ b/polygerrit-ui/app/models/flows/flows-model.ts
@@ -191,15 +191,16 @@
       name: SUBMIT_ACTION_NAME,
     };
 
+    let condition = getSubmitCondition();
+    if (autosubmitProvider?.getSubmitCondition()) {
+      condition = `${getChangePrefix()} is ${autosubmitProvider.getSubmitCondition()}`;
+    }
+
     await this.restApiService.createFlow(this.changeNum, {
       stage_expressions: [
         {
-          condition: autosubmitProvider
-            ? autosubmitProvider.getSubmitCondition()!
-            : getSubmitCondition(),
-          action: autosubmitProvider
-            ? autosubmitProvider.getSubmitAction()
-            : defaultAction,
+          condition,
+          action: autosubmitProvider?.getSubmitAction() ?? defaultAction,
         },
       ],
     });

polygerrit-ui/app/models/flows/flows-model_test.ts

diff --git a/polygerrit-ui/app/models/flows/flows-model_test.ts b/polygerrit-ui/app/models/flows/flows-model_test.ts
index de729af..2dfe5a7 100644
--- a/polygerrit-ui/app/models/flows/flows-model_test.ts
+++ b/polygerrit-ui/app/models/flows/flows-model_test.ts
@@ -6,6 +6,7 @@
 import {testResolver} from '../../test/common-test-setup';
 import {
   FlowsModel,
+  getChangePrefix,
   getSubmitCondition,
   SUBMIT_ACTION_NAME,
 } from './flows-model';
@@ -149,7 +150,7 @@
     assert.deepEqual(args[1], {
       stage_expressions: [
         {
-          condition: 'custom condition',
+          condition: getChangePrefix() + ' is custom condition',
           action: {name: 'custom action'},
         },
       ],