loki helm chart: specify default seccompProfile for the various pods

[martinbelleau-capellasystems]

Trivy security scanner finds some Medium severity config issues with loki pods, labeled 'Seccomp policies disabled'.

I would like these to be set by default in the loki helm chart.

Note that I am able to set this already through the helm chart values YAML, by specifying the podSecurityContext and containerSecurityContext, and basically copying the defaults from the original values YAML file, and adding:

seccompProfile:
type: RuntimeDefault

however I'm not sure if such modifications will lead to problems in the future. It would be nice also if internal loki testing (and all user testing which rely on defaults) would also be done with the seccompProfile enabled.