fix: we shouldn't show the amplitude warning on every ddev command

[rfay]

The Issue

When ddev has been compiled without AmplitudeAPIKey (as with brew install --HEAD ddev it shows a message warning about the situation.

However, it has been going overboard in recent versions, showing it on every command. Change it to warn only on ddev start.

The message is:

Instrumentation is opted in, but AmplitudeAPIKey is not available. This usually means you have a locally-built ddev binary or one from a PR build. It's not an error. Please report it if you're using an official release build.

Manual Testing Instructions

unset AmplitudeAPIKey
make
ddev config global --instrumentation-opt-in=true
cd <someproject>
ddev start 
ddev exec ls 

The message should show at the end of ddev start but not on ddev exec.

Automated Testing Overview

No changes.

[github-actions]

Download the artifacts for this pull request:

• all-ddev-executables.zip
• ddev-linux-amd64.zip
• ddev-linux-arm64.zip
• ddev-macos-amd64.zip
• ddev-macos-arm64.zip
• ddev-windows-amd64-installer.zip

See Testing a PR