Make watcher identify itself on disk activation

For most jobs submitted by the watcher, it identifies
itself correctly in the reason trail. However, one
instance of an OpInstanceActivateDisk job was missed.
Fix this.

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>
Fix hlint warnings found by hlint 1.9.11

Our current hlint version cannot find them yet.

Signed-off-by: Niklas Hambuechen <niklash@google.com>
Reviewed-by: Klaus Aehlig <aehlig@google.com>

Cherry-picked from: d05f1c86fcca

Signed-off-by: Klaus Aehlig <aehlig@google.com>
Reviewed-by: Niklas Hambuechen <niklash@google.com>
Merge branch 'stable-2.12' into stable-2.13

* stable-2.12
  Fix hlint warnings found by hlint 1.9.11
  Make watcher identify itself on disk activation

Signed-off-by: Niklas Hambuechen <niklash@google.com>
Reviewed-by: Petr Pudlak <pudlak@google.com>