terraform: support TBS in standalone_apm_server

[carsonip]

Motivation/summary

Support TBS in testing/infra/terraform/modules/standalone_apm_server

Checklist

• Update CHANGELOG.asciidoc
• Documentation has been updated

For functional changes, consider:

• Is it observable through the addition of either logging or metrics?
• Is its use being published in telemetry to enable product improvement?
• Have system tests been added to avoid regression?

How to test these changes

Run testing/benchmark with tfvars

apm_server_tail_sampling = true
apm_server_tail_sampling_storage_limit = "30GB"
run_standalone = true
standalone_apm_server_instance_size = "c6id.2xlarge"
worker_instance_type = "c6i.4xlarge"
standalone_apm_server_volume_type = "gp3"
standalone_apm_server_volume_size = 40

Output should contain a non-zero tbs_lsm_size e.g.

BenchmarkAgentAll-512        871         163274501 ns/op                 0 error_responses/sec        2205 errors/sec        19059 events/sec          995.0 gc_cycles        1049 max_goroutines        937528464 max_heap_alloc          4870724 max_heap_objects     1078747136 max_rss              22.21 mean_available_indexers            16854 metrics/sec           0 spans/sec      30967789 tbs_lsm_size  148710064 tbs_vlog_size                 0 txs/sec      436651105 B/op   4260866 allocs/op

Related issues

Follow up to #14985

Meta issue #14931

[mergify]

This pull request does not have a backport label. Could you fix it @carsonip? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-7.17 is the label to automatically backport to the 7.17 branch.
• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.
• backport-8.x is the label to automatically backport to the 8.x branch.

[mergify]

backport-8.x has been added to help with the transition to the new branch 8.x.
If you don't need it please use backport-skip label.

[marclop]

Very useful!