app(tests): disable flakey app tests for now (#4633)

## Describe your changes

This disable two app tests that have flake occasionally.

## Issue ticket number and link

Possibly related to #4517 

## Checklist before requesting a review

- [x] If this code contains consensus-breaking changes, I have added the
"consensus-breaking" label. Otherwise, I declare my belief that there
are not consensus-breaking changes, for the following reason:

crates/core/app/tests/app_can_sweep_a_collection_of_small_notes.rs

@@ -33,6 +33,7 @@ const COUNT: usize = SWEEP_COUNT + 1;
 /// Exercises that the app can process a "sweep", consolidating small notes.
 //  NB: a multi-thread runtime is needed to run both the view server and its client.
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+#[ignore = "Flaked in #4626"]
 async fn app_can_sweep_a_collection_of_small_notes() -> anyhow::Result<()> {
     // Install a test logger, and acquire some temporary storage.
     let guard = common::set_tracing_subscriber_with_env_filter("info".into());

crates/core/app/tests/view_server_can_be_served_on_localhost.rs

@@ -26,6 +26,7 @@ mod common;
 
 // NB: a multi-thread runtime is needed to run both the view server and its client.
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+#[ignore = "Flaked in #4627,#4632,#4624"]
 async fn view_server_can_be_served_on_localhost() -> anyhow::Result<()> {
     // Install a test logger, acquire some temporary storage, and start the test node.
     let guard = common::set_tracing_subscriber();