[CLC-432]: Fix hanging problem when source and target clusters is not running

[kutluhanmetin]

• The reason of the problem is that we forgot to handle context errors in for loop while waiting migration to be in progress, so even if we have a timeout error it waits for it to be in progress forever.
• Also this PR increases the timeout of the context, because it was 30 seconds which is same with the backend. So sometimes it used to fail with timeout, sometimes with Unable to connect to any cluster error. After increasing the timeout, user will consistently see the Unable to connect to any cluster error.

[srknzl]

seems correct, needs testing. left to qa