selftests/tc-testing: update test definitions for local resources

With resources localized on a per test basis, some tests definitions
either contain redundant commands, were wrong or could be simplified.
Update all of them to match the new requirements.

Tested-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>