Remove 'deactivate_image' config options

'deactivate_image' config option was added long
back in kilo cycle and has been deprecated for
removal.
- I584cd40a9b5f297537333336b1b9a46ccf1ddc67

This commit removes it from tempest.

Change-Id: I843d4c64f24407d9d217005d5ea59d50d7ad62e7
diff --git a/releasenotes/notes/removal-deprecated-config-options-3db535b979fe3509.yaml b/releasenotes/notes/removal-deprecated-config-options-3db535b979fe3509.yaml
index dbb6c46..2b3bb3a 100644
--- a/releasenotes/notes/removal-deprecated-config-options-3db535b979fe3509.yaml
+++ b/releasenotes/notes/removal-deprecated-config-options-3db535b979fe3509.yaml
@@ -6,3 +6,4 @@
     good to handle them.
 
     * ``[identity-feature-enabled].forbid_global_implied_dsr``
+    * ``[image-feature-enabled].deactivate_image``