Remove deprecated plugins and options for v1.40.0

### Use Case

Tracking issue for removing all options and plugins whose deprecation period expires with the 1.40.0 release. These are the entries reported as `ERROR ... removal in 1.40.0` by `./telegraf --deprecation-list`.

### Expected behavior

Each deprecated plugin/option is removed and, where applicable, a config migration is provided so existing configs keep loading.

### Tasks

Plugins to remove:

- [ ] `inputs.aerospike` -> `inputs.prometheus` with the Aerospike Prometheus Exporter
#19082
- [ ] `inputs.sflow` -> `inputs.netflow` (migration exists)
#19083
- [ ] `outputs.amon` -> no replacement, service defunct
#19084

Options to remove:

- [ ] `inputs.kafka_consumer/connection_strategy` -> `startup_error_behavior`
#19085
- [ ] `inputs.openstack/server_diagnotics` -> add `serverdiagnostics` to `enabled_services`
#19086
- [ ] `inputs.procstat` `cmdline_tag` / `pid_tag` / `supervisor_unit` -> `tag_with` / `supervisor_units` (migration exists) #19087
- [ ] `inputs.tail/from_beginning` -> `initial_read_offset` = `beginning`
#19088
- [ ] `inputs.zookeeper/enable_tls` -> `tls_enable`
#19089
- [ ] `outputs.kafka` `ca` / `certificate` / `key` -> `tls_ca` / `tls_cert` / `tls_key`
#19090