MON-3961: inject proxy env variables in Alertmanager

[simonpasquier]

• [ ] I added CHANGELOG entry for this change.
• [X] No user facing changes, so no entry in CHANGELOG was needed.

[openshift-ci-robot]

@simonpasquier: This pull request references MON-3961 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the task to target the "4.17.0" version, but no target version was set.

In response to [this](https://github.com/openshift/cluster-monitoring-operator/pull/2424): > > >* [ ] I added CHANGELOG entry for this change. >* [X] No user facing changes, so no entry in CHANGELOG was needed. > Instructions for interacting with me using PR comments are available [here](https://prow.ci.openshift.org/command-help?repo=openshift%2Fcluster-monitoring-operator). If you have questions or suggestions related to my behavior, please file an issue against the [openshift-eng/jira-lifecycle-plugin](https://github.com/openshift-eng/jira-lifecycle-plugin/issues/new) repository.

[openshift-ci[bot]]

Skipping CI for Draft Pull Request. If you want CI signal for your change, please convert it to an actual PR. You can still manually trigger a test run with /test all

[simonpasquier]

/skip

[simonpasquier]

/retest-required

[jan--f]

/lgtm

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: jan--f, simonpasquier

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/openshift/cluster-monitoring-operator/blob/master/OWNERS)~~ [jan--f,simonpasquier] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD 5c4e4e6708005e1ff0d7d28a10b6bfe1fcacf621 and 2 for PR HEAD 38f4f8899b90b9fe9a206967b4d04b112a30bd72 in total

[openshift-ci[bot]]

@simonpasquier: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/versions	38f4f8899b90b9fe9a206967b4d04b112a30bd72	link	false	/test versions

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository. I understand the commands that are listed [here](https://go.k8s.io/bot-commands).

[simonpasquier]

/retest-required

[openshift-bot]

[ART PR BUILD NOTIFIER]

Distgit: cluster-monitoring-operator This PR has been included in build cluster-monitoring-operator-container-v4.17.0-202408051414.p0.g960c4e6.assembly.stream.el9. All builds following this will include this PR.