add securityContext to the manager containers

[AshleyDumaine]

kind/bug

What this PR does / why we need it: Without securityContext set for the manager containers, RKE2 bootstrap and control-plane providers cannot be installed into an RKE2 cluster with cis-profile set (e.g. creating a hardened RKE2 cluster and pivoting the management cluster into it).

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #384

Special notes for your reviewer:

Checklist:

• squashed commits into logical changes
• includes documentation
• adds unit tests
• adds or updates e2e tests

[furkatgofurov7]

@AshleyDumaine thanks for the contribution.
I was checking the previous releases of the CAPI, and noticed they introduced same changes in release-1.4 minor version. As we strive to align with upstream and CAPI in general, can I ask you to take a look at https://github.com/kubernetes-sigs/cluster-api/pull/7831/files#diff-8d4b80dac52bef6a87376c16699a47555f567a9c7b68408965e37b68dedee6cb and add the missing bits in this patch?

[AshleyDumaine]

@AshleyDumaine thanks for the contribution. I was checking the previous releases of the CAPI, and noticed they introduced same changes in release-1.4 minor version. As we strive to align with upstream and CAPI in general, can I ask you to take a look at https://github.com/kubernetes-sigs/cluster-api/pull/7831/files#diff-8d4b80dac52bef6a87376c16699a47555f567a9c7b68408965e37b68dedee6cb and add the missing bits in this patch?

Sounds good, just pushed the update 👍

[furkatgofurov7]

@alexander-demicev @salasberryfin @Danil-Grigorev

[alexander-demicev]

thanks!