Optionally give ability to route at events to the logging instance (in addition to pushing to cos bucket)

[vburckhardt]

Description

terraform-ibm-observability-da/solutions/instances/main.tf

Line 126 in c267702

module.observability_instance.activity_tracker_targets["cos-target"].id

Underlying module already supports it https://github.com/terraform-ibm-modules/terraform-ibm-observability-instances/blob/5aa73fba04fc7f6a4b1076c04cde00dc43851aa3/modules/activity_tracker/main.tf#L150

[ocofaigh]

#56