Remove labels if description changed (#7043)

Author: maximyurchuk

.github/workflows/pr_labels.yaml

@@ -32,11 +32,26 @@ jobs:
               ['* Documentation', 'documentation'],
               ['* Not for changelog', 'not-for-changelog']
             ];
-            if (!description) return;
+            // remove all labels owned by current script 
+            for (let pair of mapping) {
+              try {
+                const result = await github.rest.issues.removeLabel({
+                  owner,
+                  repo,
+                  issue_number: prNumber,
+                  name: pair[1]
+                });
+                console.log('Removed label', pair[1]);
+              } catch(e) {
+                console.log(e);
+              }
+            }
+            // add first encountered label
             for (let pair of mapping) {
               if (!description.includes(pair[0])) continue;
+              // add label
               try {
-                 const result = await github.rest.issues.addLabels({
+                const result = await github.rest.issues.addLabels({
                   owner,
                   repo,
                   issue_number: prNumber,
@@ -46,5 +61,5 @@ jobs:
               } catch(e) {
                 console.log(e);
               }
-              return;
+              break;
             }