chore(table): remove redundant condition (#7345)

src/cdk/table/row.ts

@@ -44,7 +44,7 @@ export abstract class BaseRowDef {
     // Create a new columns differ if one does not yet exist. Initialize it based on initial value
     // of the columns property or an empty array if none is provided.
     const columns = changes['columns'].currentValue || [];
-    if (!this._columnsDiffer && columns) {
+    if (!this._columnsDiffer) {
       this._columnsDiffer = this._differs.find(columns).create();
       this._columnsDiffer.diff(columns);
     }