MON-3701: clean-up injection of trusted CA bundle for main 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-3701 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 "4.16.0" version, but no target version was set.

In response to [this](https://github.com/openshift/cluster-monitoring-operator/pull/2310): > > >* [ ] I added CHANGELOG entry for this change. >* [ ] 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.

[simonpasquier]

/retest-required

[simonpasquier]

/retest-required

[simonpasquier]

/skip

[simonpasquier]

/test e2e-aws-ovn-upgrade

[simonpasquier]

/skip

[openshift-ci[bot]]

@simonpasquier: The following tests 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/e2e-aws-ovn-single-node	ca92ea3cbf8b9375883a28485074e9a93b6a8ebc	link	false	/test e2e-aws-ovn-single-node
ci/prow/versions	ca92ea3cbf8b9375883a28485074e9a93b6a8ebc	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/test-infra](https://github.com/kubernetes/test-infra/issues/new?title=Prow%20issue:) repository. I understand the commands that are listed [here](https://go.k8s.io/bot-commands).

[simonpasquier]

/skip

[simonpasquier]

/hold want to test a small variation

[machine424]

/hold

[machine424]

/lgtm please unhold when it's ok for you.

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: machine424, 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)~~ [machine424,simonpasquier] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[simonpasquier]

/hold cancel