Description of problem:
When we edit an existing hook, the result is that the fields "executionNamespace" and "serviceAccount" are empty in the migration plan. Showing the MigPlan a critical condition.

Version-Release number of selected component (if applicable):
KONVEYOR 1.2

How reproducible:
Always

Steps to Reproduce:
1. Create a migration plan with a hook
2. Edit the migration plan created in step 1. And click Edit hook on the "Hooks" screen.
3. Click "Update Hook" and save the existing hook without doing any modification.

Actual results:

This error is displayed after the plan edition:

Failed to validate migration plan  XXXXXX.
Critical
The serviceAccount specified is invalid, DNS-1123 subdomain regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'
Critical
The executionNamespace specified is invalid, DNS-1123 label regex used for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?'.

    - category: Critical
      lastTransitionTime: "2020-04-29T14:27:50Z"
      message: The serviceAccount specified is invalid, DNS-1123 subdomain regex used
        for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*'
      reason: NotSet
      status: "True"
      type: InvalidHookSAName
    - category: Critical
      lastTransitionTime: "2020-04-29T14:27:50Z"
      message: The executionNamespace specified is invalid, DNS-1123 label regex used
        for validation is '[a-z0-9]([-a-z0-9]*[a-z0-9])?'.
      reason: NotSet
      status: "True"
      type: InvalidHookNSName
    observedDigest: 727c5556c16c0dc2d8dd04cfe4e2a4855b99654b7686a1bcd3a0fa0e5821772e




When we check the MigPlan information, we can see that the "serviceAccount" and "executionNamespaces" fiels are empty:

    hooks:
    - executionNamespace: ""
      phase: PreBackup
      reference:
        name: fail
        namespace: openshift-migration
      serviceAccount: ""


Expected results:
The hook should have the right values, and the migration plan should show no critical condition.

Additional info: