chore: wait for downloads getting removed on context.close() (#23500)

Before there was a race, that we ran into this code:


9cd49d5dd5/packages/playwright-core/src/server/browserContext.ts (L236-L237)

and then into this code:


9cd49d5dd5/packages/playwright-core/src/server/browserContext.ts (L429-L431)

which had the side effect, that the first call did not wait. Then
immediately clears the downloads Set and then the second call is a NOOP.
This ends up that the the removal of the downloads can happen after the
context is closed, hence the test is flaky.

Relates to https://github.com/microsoft/playwright/pull/6151 where it
got introduced. So something for @yury-s.

Fixes https://github.com/microsoft/playwright/issues/22525

packages/playwright-core/src/server/browserContext.ts

@@ -232,9 +232,12 @@ export abstract class BrowserContext extends SdkObject {
       // at the same time.
       return;
     }
+    const gotClosedGracefully = this._closedStatus === 'closing';
     this._closedStatus = 'closed';
+    if (!gotClosedGracefully) {
       this._deleteAllDownloads();
       this._downloads.clear();
+    }
     this.tracing.dispose().catch(() => {});
     if (this._isPersistentContext)
       this.onClosePersistent();