Container Repository samples issues

[v-xuto]

Section link1:

Reason1:
for tag in tags[3:]:
TypeError: 'ItemPaged' object is not subscriptable.

Suggestion1:
Update to:

for tag in client.list_tag_properties(repository, order_by=TagOrder.LAST_UPDATE_TIME_DESCENDING):
    tag_count += 1
    if tag_count > 3:
        client.delete_tag(repository, tag.name)   

Suggestion2:
Add code:

if __name__ == "__main__":
    sample = DeleteOperations()
    sample.delete_old_tags()   

Section link:

Suggestion:
Add await before sample.delete_old_tags().

@jongio for notification.

[v-xuto]

Close this issue, due to PR #19661 merged.