compact: Add securityContext to Thanos compact container

[kaznak]

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

The kube-thanos-compact-default-params.libsonnet file already defines a securityContextContainer parameter, but it is not currently used.

kube-thanos/jsonnet/kube-thanos/kube-thanos-compact-default-params.libsonnet

Lines 52 to 60 in 6fedb04

	securityContextContainer:: {
	runAsUser: defaults.securityContext.runAsUser,
	runAsGroup: defaults.securityContext.runAsGroup,
	runAsNonRoot: defaults.securityContext.runAsNonRoot,
	seccompProfile: defaults.securityContext.seccompProfile,
	allowPrivilegeEscalation: false,
	readOnlyRootFilesystem: true,
	capabilities: { drop: ['ALL'] },
	},

Because of this missing reference, the generated manifests trigger Pod Security Admission warnings or may even be rejected under restricted policies.

This PR applies the securityContextContainer parameter to the compact container so that the generated manifests comply with restricted PodSecurity standards.

Verification

I applied the manifests generated from this branch to my cluster, and the Pod Security Admission warning was successfully suppressed.