When an error creating a pipeline occurs, we log all the pipeline
parameters, including the push options, in an error log and in
Sentry. However, since push options are flattened into unique keys
(e.g. `merge_request.label=gitlab-ci`, `ci.variable.MY_VARIABLE=test`),
it's easy to generate many unique keys, which may exceed the
Elasticsearch limit of 1000.

To avoid this from happening, this commit drops the `push_options` field
from the log. These generally shouldn't be needed to understand why
a pipeline failed to create.

Closes https://gitlab.com/gitlab-org/gitlab/issues/202129