Set status.runtimeImage value after running function with a new image

[pPrecel]

Description:

Right now we update the status.runtimeImage field almost at the beginning of the reconciliation which causes a few disadvantages because for example in this scenario:

1. create a function with the nodejs18 runtime
2. wait until the function is ready
3. update runtime to nodejs20
4. function fails on build because functions code does not support newer nodejs version

In such case, we would have in the status.runtimeImage field a newer version of an image that is not true because it failed on the build stage and right now on the cluster older version of this function is working.

@dbadura suggests that the status should reflect an actual version of the configuration, not the desired one