Description of problem:
Starting pipelines from web ui and using users with "@" character in the name will fail with this error:

>Error "Invalid value: "username": a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue', or 'my_value', or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?')" for field "metadata.labels".

Version-Release number of selected component (if applicable):
Openshift Container Platform 4.5
OpenShift Pipelines Operator 1.0.1

Actions

How reproducible:
100% reproducible

Steps to Reproduce:
1. Create a pipeline
2. Try to start the pipeline from web UI by user that has "@" character in the name


Actual results:
Error "Invalid value: "username": a valid label must be an empty string or consist of alphanumeric characters, '-', '_' or '.', and must start and end with an alphanumeric character (e.g. 'MyValue', or 'my_value', or '12345', regex used for validation is '(([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9])?')" for field "metadata.labels".

Expected results:
It should start

Additional info:
It prevents users in clusters that use google identity provider, or in general any user with "@" character in the name, to start pipelines.