[vm launcher] change nightly and latest launcher test to manual (ray-…

…project#48774)

nightly is inherently unstable, and latest is just last stable release.
neither of them should block releases

Signed-off-by: Lonnie Liu <lonnie@anyscale.com>
Signed-off-by: hjiang <dentinyhao@gmail.com>

release/release_tests.yaml

@@ -4956,7 +4956,7 @@
   group: cluster-launcher-test
   working_dir: ../python/ray/autoscaler/
 
-  frequency: nightly
+  frequency: manual
   team: clusters
   cluster:
     byod: {}
@@ -4971,7 +4971,7 @@
   group: cluster-launcher-test
   working_dir: ../python/ray/autoscaler/
 
-  frequency: nightly
+  frequency: manual
   team: clusters
   cluster:
     byod: {}