Describe the bug
operator diagnose will report an error about incomplete Stackdriver configuration, even if all Stackdriver
keys are omitted from the telemetry stanza (i.e., if you're using only dogstatsd or another backend).

To Reproduce
Steps to reproduce the behavior:

Given a config file like the following:

# vault-with-dogstatsd.hcl

disable_cache = true
disable_mlock = true
ui = true

listener "tcp" {
	address = "127.0.0.1:8200"
}

backend "consul" {
	advertise_addr = "foo"
	token = "foo"
}

telemetry {
	dogstatsd_tags = ["tag1:value"]
	dogstatsd_addr = "127.0.0.1:8164"
}

cluster_addr = "127.0.0.1:8201"

Run vault operator diagnose -config=vault-with-dogstatsd.hcl and observe the output contains:

  [ failure ] Check Telemetry: incomplete Stackdriver telemetry configuration, missing stackdriver_project_id

Expected behavior
Because the configuration is full and valid for dogstatsd, the diagnose output should not return any failures.

Environment:

• Vault Server Version (retrieve with vault status): 1.21.0
• Vault CLI Version (retrieve with vault version): 1.21.0
• Server Operating System/Architecture: macos, arm64

Vault server configuration file(s): see above for sample, as part of reproduction instructions.

Additional context
This bug is caused by a small glitch in the code. I have a fix which I will open up as a PR immediately after opening this issue.