fix: generate examples failing bgp_session (#198)

generate examples was failing since some explicitly excluded examples
had been renamed in terraform

"metal_bgp_session/example_1.tf" -->
"equinix_metal_bgp_session/example_1.tf"
"metal_connection/\*" --> "equinix_metal_connection/\*"

I have also removed some manually created equinix_metal_connection
examples, in order to use the ones available in Terraform.
- examples/metal/connection/example_metal_billed
- examples/metal/connection/example_fabric_billed

However, some of them need to be fixed first in terraform
equinix/terraform-provider-equinix#777, those
still specified in the
[EXCLUDE_TF_EXAMPLES](https://github.com/equinix/pulumi-equinix/compare/fix-generate-examples?expand=1#diff-0371a6843acadceb847895dd7de8ae7e51e24f5bb121e9591fb2798cbb7a25b9L5)
list

"equinix_metal_connection/shared_no_token_metal_to_fabric.tf" \
"equinix_metal_connection/shared_token_fabric_port_to_metal.tf" \
"equinix_metal_connection/shared_token_metal_to_csp.tf"

This will fix the issue in
"https://github.com/equinix/pulumi-equinix/actions/runs/10692829858".
Adding also ">&2" in the echo commands to ensure that log messages are
sent to standard error output and we can trace them in the gh action