readyset-{mysql,psql}: De-ignore some old ignored tests

These are passing now, so let's de-ignore them!

Change-Id: I7d9432dccc3ab2aeb3d7d7fb32b3dc3498325ae4
Reviewed-on: https://gerrit.readyset.name/c/readyset/+/4874
Reviewed-by: Dan Wilbanks <dan@readyset.io>
Tested-by: Buildkite CI

readyset-mysql/tests/fallback.rs

@@ -51,7 +51,6 @@ async fn create_table() {
 
 #[tokio::test(flavor = "multi_thread")]
 #[serial]
-#[ignore] // alter table not supported yet
 async fn add_column() {
     let (opts, _handle, shutdown_tx) = setup().await;
     let mut conn = mysql_async::Conn::new(opts).await.unwrap();

readyset-psql/tests/fallback.rs

@@ -185,7 +185,6 @@ async fn unsupported_query_ad_hoc() {
 
 #[tokio::test(flavor = "multi_thread")]
 #[serial]
-#[ignore] // needs proper detection of reads vs writes through fallback
 async fn prepare_execute_fallback() {
     let (config, _handle, shutdown_tx) = setup().await;
     let client = connect(config).await;