DPL: mark o2-dpl-input-proxy as a proxy

[ktf]

DPL: mark o2-dpl-input-proxy as a proxy

[github-actions]

REQUEST FOR PRODUCTION RELEASES:
To request your PR to be included in production software, please add the corresponding labels called "async-" to your PR. Add the labels directly (if you have the permissions) or add a comment of the form (note that labels are separated by a ",")

+async-label <label1>, <label2>, !<label3> ...

This will add <label1> and <label2> and removes <label3>.

The following labels are available
async-2023-pbpb-apass3
async-2023-pbpb-apass4
async-2022-pp-apass6-2023-PbPb-apass2
async-2022-pp-apass4
async-2022-pp-apass4-accepted
async-2022-pp-apass6-2023-PbPb-apass2-accepted
async-2023-pbpb-apass3-accepted
async-2023-pbpb-apass4-accepted
async-2023-pp-apass4
async-2023-pp-apass4-accepted

[ktf]

@davidrohr I have checked again in a standalone test this works fine and added a similar label to a few more places (see #13124). For the record, one can also add labels by adding --labels <input-proxy-name>:input-proxy.